Glyptochelone (Cretaceous turtle) redescribed + snake gape + avian wing muscles + tetrapod tracks from Pennsylvanian of Chile + Chicxulub impact structure + more
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Ben Creisler
Oct 2, 2025, 5:29:56 PMOct 2
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Ben Creisler
Some recent non-dino papers:
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Juliette C. L. Menon & Walter G. Joyce (2025)
A redescription of Glyptochelone suyckerbuykii (Ubaghs, 1879), an enigmatic fossil sea turtle (Chelonioidea) from the Maastrichtian of the Netherlands and Belgium, sheds new light on fossil sea turtle shell variation and neural bone homology
Swiss Journal of Palaeontology 144: 62
doi: https://doi.org/10.1186/s13358-025-00389-y
https://link.springer.com/article/10.1186/s13358-025-00389-y
We here provide a redescription the Late Cretaceous (Campanian–Maastrichtian) fossil marine turtle Glyptochelone suyckerbuykii to document its anatomy and intraspecific variation. This redescription highlights the complete absence of a nuchal pedestal, presence of a radiating shell surface texture pattern easily differentiated from that of coeval marine turtles, and the presence of interneural elements, a characteristic unique among Late Cretaceous turtles. A phylogenetic analysis suggests that Glyptochelone suyckerbuykii is located at the base of Dermochelyidae, a dubious result likely resulting from missing data. To allow constructing phylogenetic characters based on the presence of supernumerary neural elements, we suggest a revised classification for the midline column of the carapace of turtles based on novel homology criteria as consisting of neurals, which are outgrowths of the neural arches, as opposed to preneurals, interneurals, and postneurals, which are independent bones that form in front, within, and posterior to the neural column, respectively. We suggest use of this novel classification in future phylogenetic analysis.
Juliette C. L. Menon & Walter G. Joyce (2025)
A redescription of Glyptochelone suyckerbuykii (Ubaghs, 1879), an enigmatic fossil sea turtle (Chelonioidea) from the Maastrichtian of the Netherlands and Belgium, sheds new light on fossil sea turtle shell variation and neural bone homology
Swiss Journal of Palaeontology 144: 62
doi: https://doi.org/10.1186/s13358-025-00389-y
https://link.springer.com/article/10.1186/s13358-025-00389-y
We here provide a redescription the Late Cretaceous (Campanian–Maastrichtian) fossil marine turtle Glyptochelone suyckerbuykii to document its anatomy and intraspecific variation. This redescription highlights the complete absence of a nuchal pedestal, presence of a radiating shell surface texture pattern easily differentiated from that of coeval marine turtles, and the presence of interneural elements, a characteristic unique among Late Cretaceous turtles. A phylogenetic analysis suggests that Glyptochelone suyckerbuykii is located at the base of Dermochelyidae, a dubious result likely resulting from missing data. To allow constructing phylogenetic characters based on the presence of supernumerary neural elements, we suggest a revised classification for the midline column of the carapace of turtles based on novel homology criteria as consisting of neurals, which are outgrowths of the neural arches, as opposed to preneurals, interneurals, and postneurals, which are independent bones that form in front, within, and posterior to the neural column, respectively. We suggest use of this novel classification in future phylogenetic analysis.
Free pdf:
Maricci Basa, Neal Anthwal, Ryan N. Felice & Abigail S. Tucker (2025)
The wide gape of snakes: A comparison of the developing mandibular symphysis in sauropsids
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.70050
https://onlinelibrary.wiley.com/doi/10.1111/joa.70050
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1111/joa.70050
The origin and evolution of snakes has been marked by the acquisition of many morphological and functional novelties, one of which is the possession of a highly kinetic skull allowing for the consumption of prey that are often larger than their head diameter. One feature of the iconic wide gape of macrostomate (large-mouthed) snakes is due to changes in the rostral midline where the left and right hemi-mandible come together. Across vertebrates, the two sides of the lower jaw are held together by the mandibular symphysis. In snakes, the two halves of the lower jaw do not fuse and the symphysis remains free, facilitating gape expansion. The symphysis has previously been explored in lizards and crocodiles, where ligamentous fibres and cartilages span the joint. Here, we compared the anatomy of the forming ‘free’ mandibular symphysis in the corn snake (Pantherophis guttatus) to symphysis development in two lizards, the veiled chameleon (Chamaeleo calyptratus) and the ocelot gecko (Paroedura picta), and an outgroup sauropsid, the chicken (Gallus gallus domesticus). Microcomputed tomography imaging, whole-mount skeletal staining and histology staining confirmed the absence of bone and cartilage fusion at the mandibular symphysis in the corn snake during development, in contrast to the complete fusion of cartilage, but not bone, in both lizards and the fusion of the bone in the chick. Trichrome staining under circular polarised light and whole fast green staining highlighted that, while the symphyseal region was populated by a dense network of collagen fibres, the snake hemi-mandibles were not connected across the rostral region by this fibrous network. Instead, collagen fibres extended backwards and around the snake mental groove to an intermandibular nodule. This nodule attached to the midline dorsally, allowing integration of the movement of the soft and hard tissues. Our analysis highlights the adaptations required to allow extreme lower jaw mobility and independence of the two sides of the jaw as found in macrostomate snakes.
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Free pdf:
D. Charles Deeming & María Clelia Mosto (2025)
Holding a wing horizontal: Roles for muscles of the pectoral girdle other than the main two flight muscles
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.70051
https://onlinelibrary.wiley.com/doi/full/10.1111/joa.70051
Whilst many birds glide briefly with wings held horizontally, some species maintain this posture for extended periods during soaring. This is considered possible because of the contraction of the m. pectoralis that holds the wing in place, although albatrosses seem to have a physical shoulder lock that helps with this action. However, studies of this flight style have not considered the cranially orientated long-axis rotation of the humerus induced by the contraction of the main flight muscles that would depress the ulna and change the angle of the aerofoil downwards. This study explored whether the m. deltoideus major helps counteract this rotation. Muscle masses were collated from the literature and from dissections of birds to allow exploration of the allometry of muscle masses versus body mass. All muscles exhibited isometry with body mass, but relative to the size of the m. pectoralis, the m. deltoideus major was large but only in a few species that regularly soar or glide for long periods. By contrast, other elevator muscles were less variable among species. The presence of relatively large deltoideus major muscles in soaring species was suggestive that this muscle, since it originates on the scapula extending caudally and inserting on the dorsal humerus, may counteract humeral long-axis rotation around its longitudinal axis during contraction of the breast muscles. The results of this study are suggestive of previously unconsidered substantial roles for other muscles of the pectoral girdle and forelimb during different flight styles in birds.
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Sebastian Voigt, Philippe Moisan, Gonzalo Sánchez, Erick Vargas & Héctor Olivares (2025)
Tetrapod tracks and other trace fossils from the Chinches Formation (Andean Precordillera, northern Chile): indication for Pennsylvanian age and glacial influence
Journal of South American Earth Sciences 105804
doi: https://doi.org/10.1016/j.jsames.2025.105804
https://www.sciencedirect.com/science/article/abs/pii/S0895981125004663
Research highlights
1. Chilean Chinches Formation younger than previously proposed.
2. Diverse and probably glacially influenced ichnofossil assemblage.
3. First pelycosaur-grade synapsid tracks from Earth’s southern hemisphere.
Abstract
The Chinches Formation is an up to 3,000 m thick succession of poorly studied Paleozoic sedimentary deposits cropping out in isolated high mountain areas on the southern edge of the Atacama Desert, northern Chile. During a recent scientific expedition to various outcrops of the formation, an abundant array of trace fossils was discovered that provides new insight into the stratigraphic age and depositional environment of the fossil-bearing sedimentary deposits. The recorded ichnofauna of the Chinches Formation includes invertebrate traces (Cochlichnus, Diplichnites, Glaciichnium, Vagorichnus) and vertebrate traces (Undichna, Dimetropus, Dromopus, Limnopus, Matthewichnus) referred to locomotion and feeding activity of annelids, arthropods, fish and tetrapods. The assemblage combines elements of the Scoyenia and Mermia ichnofacies suggesting fluvio-lacustrine depositional conditions, though a marine influence cannot be ruled out for parts of the sequence. Especially the non-tetrapod trace fossils show similarities with typical glacio-lacustrine late Paleozoic Gondwanan ichnofaunas. Based on the mixed amphibian-early amniote tetrapod ichnofauna, a late Carboniferous (Pennsylvanian) age of the Chinches Formation is proposed. The study area yields the only occurrence of Carboniferous tetrapod tracks in the present-day southern hemisphere and gives evidence that Pennsylvanian land vertebrate faunas of the tropics and mid-southern latitudes were basically similar by comprising temnospondyls, lepospondyls, early synapsids and lacertoid-like sauropsids. The Chinches Formation has great potential to study the effect of the Late Paleozoic Ice Age on continental and maybe shallow marine ecosystems in higher paleolatitudes.
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Free pdf:
Yaroslav Garashchenko & Ilja Kogan, Miroslaw Rucki (2025)
Statistical Analysis of Digital 3D Models of a Fossil Tetrapod Skull from µCT and Optical Scanning
Sensors 25(19): 6084
doi: https://doi.org/10.3390/s25196084
https://www.mdpi.com/1424-8220/25/19/6084
The quality of digital 3D models of fossils is important from the perspective of their further usage, either for scientific or didactical purposes. However, fidelity evaluation has rarely been attempted for digitized fossil objects. In the present research, a 3D triangulated model of the unique skull of Madygenerpeton pustulatum was built using an YXLON µCT device. The comparative analysis was performed using models obtained from seven optical surface-scanning systems. Methodology for accuracy assessment involved the determination of distances between the points in pairs of models, interchanging the reference and tested ones. Statistical significance testing using paired t-tests was performed. In particular, it was found that the YXLON µCT model was closest to the one obtained from AICON SmartScan, exhibiting an average distance of ∆𝑑 = −0.0183 mm with a standard deviation of σ{∆d} = 0.0778 mm, which is close to the permissible error of 20 µm given in technical specifications for AICON scanners. It was demonstrated that the analysis maintained measurement validity even though the YXLON model consisted of 23.8 M polygons and the AICON model consisted of 13.9 M polygons. Comparison with other digital models demonstrated that the fidelity of the triangulated µCT model made it feasible for further research and dissemination purposes.
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Free pdf:
S.P.S. Gulick, P. Kaskes, C.M. Lowery, A.S.P. Rae, S.M. Tikoo (2025)
From impact to extinction to recovery: Discoveries of IODP-ICDP Expedition 364 to the Chicxulub impact structure
Marine Geology 107661
doi: https://doi.org/10.1016/j.margeo.2025.107661
https://www.sciencedirect.com/science/article/pii/S0025322725001860
Highlights
Summary of major results and next research steps from the IODP-ICDP scientific drilling expedition to the Chicxulub impact structure
Dynamic collapse model of peak ring impact basin formation validated
Crater filled with impact melt rock and melt-bearing breccia (suevite) and underwent ocean resurge
Chicxulub unequivocably linked to Cretaceous-Paleogene mass extinction containing the global iridium layer and producing dust, sulfate aerosols, and soot
Recovery of life in crater is similar to global ocean with primary succession driven by picoplankton before transitioning over 100 s of kyr to plankton dominated communities
Chicxulub subsurface contained extant thermophilic biota and evidence for long-lived hydrothermal system
Abstract
In 2016, International Ocean Discovery Program Expedition 364, with support from the International Continental Scientific Drilling Program, drilled into the peak ring of the Chicxulub impact structure, famous for its causal link to the mass extinction at the end of the Cretaceous. In this summary paper, we discuss key findings from Site M0077 on the cratering processes, marine ecosystem recovery after the mass extinction, and the post-impact hydrothermal system and habitability of the impact structure. Important results include (1) the confirmation of the dynamic collapse model of peak ring formation, (2) insights into impactite emplacement processes on Earth, where water is a key component, (3) discovery of the iridium anomaly within the impact basin, unequivocally linking the Chicxulub impact basin to the global Cretaceous-Paleogene (K-Pg) boundary layer, (4) evidence for key atmospheric inputs of dust, sulfate aerosols, and soot, all likely contributing to global cooling and reduction of photosynthesis as drivers for extinction, (5) rapid recovery of life within the ocean overlying the crater, including a primary succession driven by in part by picoplankton before a transition over 100 s kyr to diversifying planktic communities, and (6) the presence of a long-lived hydrothermal system with extant thermophilic life in the buried peak ring 66 Myr later. The Chicxulub crater represents exceptional scientific opportunity in that it bridges planetary science, impact dynamics, and astrobiology; the integration of such findings continue to reveal the transformative power of asteroid impacts as a major geologic and biologic process.
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Free pdf:
Francesca Galasso, Anja B. Frank & William J. Foster (2025)
Heavy metal toxicity and its role as a major driver of past biodiversity crises
Communications Earth & Environment 6: 780
doi: https://doi.org/10.1038/s43247-025-02781-5
https://www.nature.com/articles/s43247-025-02781-5
Whether today’s heavy metal pollution constitutes an unprecedented threat to biodiversity remains unresolved. Although evidence of metal enrichment exists for several deep-time biotic crises, direct causal links to extinction are lacking. This review synthesizes the current understanding of the relationship between elevated environmental heavy metal concentrations and biological responses, including malformations and extinctions, across marine and terrestrial ecosystems. Drawing on analogies from modern environments, we assess the role of heavy metal toxicity in past mass extinction events. While some studies implicate heavy metals as primary extinction drivers, shown for instance by sporomorphs malformations, others interpret these signals as post-extinction artifacts linked to organic matter decomposition. Our analysis highlights the influence of normalization methods, particularly sulfur-based approaches, and emphasizes the role of metal bioavailability as a key factor influencing biological effects. Further research is needed to clarify the role of heavy metals in Earth’s biotic history and ongoing environmental risks.
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Francesca Galasso, Anja B. Frank & William J. Foster (2025)
Heavy metal toxicity and its role as a major driver of past biodiversity crises
Communications Earth & Environment 6: 780
doi: https://doi.org/10.1038/s43247-025-02781-5
https://www.nature.com/articles/s43247-025-02781-5
Whether today’s heavy metal pollution constitutes an unprecedented threat to biodiversity remains unresolved. Although evidence of metal enrichment exists for several deep-time biotic crises, direct causal links to extinction are lacking. This review synthesizes the current understanding of the relationship between elevated environmental heavy metal concentrations and biological responses, including malformations and extinctions, across marine and terrestrial ecosystems. Drawing on analogies from modern environments, we assess the role of heavy metal toxicity in past mass extinction events. While some studies implicate heavy metals as primary extinction drivers, shown for instance by sporomorphs malformations, others interpret these signals as post-extinction artifacts linked to organic matter decomposition. Our analysis highlights the influence of normalization methods, particularly sulfur-based approaches, and emphasizes the role of metal bioavailability as a key factor influencing biological effects. Further research is needed to clarify the role of heavy metals in Earth’s biotic history and ongoing environmental risks.
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Free pdf:
Shilong Guo, Wang Ma, Liang Chen, Yunyu Tang, Mengfei Li, Yanchen Zhao, Xinru Deng, Jialiang Zhuang, Yingjie Qiao, Hui Fang, Chungkun Shih, Zhigang Guo, Conrad C. Labandeira & Dong Ren (2025)
The effects of sensitive environmental indicators in interpreting faunas of the past: a case study from the Jurassic of China
Palaeontology 68(5): e70023
doi: https://doi.org/10.1111/pala.70023
https://onlinelibrary.wiley.com/doi/10.1111/pala.70023
The effects of sensitive environmental indicators in interpreting faunas of the past: a case study from the Jurassic of China
Palaeontology 68(5): e70023
doi: https://doi.org/10.1111/pala.70023
https://onlinelibrary.wiley.com/doi/10.1111/pala.70023
The Yanliao Biota is a key Mesozoic terrestrial Lagerstätte in China. It is dominated by invertebrates, particularly clam shrimp, water boatmen and mosquitoes. Vertebrates are rare, with occasional sturgeons and salamanders. Most Chinese researchers suggest that there may be a spatiotemporal and physical association between fragmentation and erosion of the North China Craton (NCC) circumscribing the evolution of the Middle Jurassic Yanliao and Early Cretaceous Jehol faunas that are separated by c. 40 million years. However, recent research has primarily focused on the broad relationships between the tectonic behaviour of the North China Craton and events involving biodiversity and macroevolutionary expansion of these faunas whilst simultaneously neglecting quantitative analyses of community structure and the effects of environmental factors. By integrating species abundances and community co-occurrence networks with geochemical data, we identified salinity as being strongly associated with differentiation among the fossil communities of the Early Yanliao fauna during the late Middle Jurassic interval. Furthermore, our results ruled out humidity, temperature, water carbon-to-nitrogen ratio, and water oxidation conditions as factors with strong correlations, indirectly reinforcing the hypothesis that structural alteration of the North China Craton significantly influenced development and extinction of the Yanliao biota.
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Gregory Paul
Oct 8, 2025, 9:14:15 PM (11 days ago) Oct 8
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Paul, G. S. (2025)
Stratigraphic and anatomical evidence for multiple Titanosaurid dinosaur taxa in the late Late Cretaceous of southwestern North America. Geology of the Intermountain West 12: 201-220.
As I am sure you all have thought, it has long been suspicious that just Alamosaurus sanjuanensis was the sole titanosaur taxon dwelling in the entire SW USA and Mexico for most or all the Maastrichtian and perhaps even back into the late Campanian. As I do the field guides I sometime look at taxa entries to see if they need reconsideration. Taking a look at the mid Maastrichtian Alamo holotype and late Maastrichtian North Horn titanosaur scapulae it became obvious they are not the same beast. At the same time, the late Maastrichtian juvenile titanosaur scapula from Texas is a dead ringer for the contemporary UT shoulder blade. Hence it was time to show that SW titanosaur diversity was of course substantial in accord with Darwinian biology.
A reviewer said there is more variation in the scapulae of Camarasaurus supremus from the Garden Park quarry than between the titanosaur blades. So I looked up Osborn and Mook and sure enough those pectoral elements are actually quite similar, so I added a figure showing that, that should be useful for future work on intraspecies variation.
This is my first stratigraphic chart, which I was reluctant to do because it is not my geothing. Did the best I could with the often ambiguous data.
I have a personal connection with the holotype of Utetitan zellaguymondeweyae. It is from the North Horn Formation in Joe’s Valley in the Wasatch Plateau in central UT. Which is 20 miles SW of Huntington, where my mother’s mother was born (1901-2002) and raised (left the town in her late teens -- about the same distance straight to the east of the town is the Cleveland-Lloyd quarry). My mother is buried in the town. To the NE is Price where my Aunt Sylvia’s Greek relations are centered. When a kid I spent some summers in the Salt Lake Valley, largely with Sylvia and her family (she still lives in the same house under Mt Olympus). When on the Dr Bob led JHU expedition in 1978 we drove through Price and Huntington on our way to the Utetitan quarry location to check out the sedimentology (very like the Morrison), I did not know at the time the family connections (when he learned about our quick look at the NH site Jim Jenson complained in the SVP members bulletin long discontinued, he was kinda uptight).
In the late 1930s my preteen mom would spend summers with her Guymon relations in Huntington, which is why she chose to be buried there. In WW 2 her younger brother Gordon did the same, sometimes riding up into the Wasatch hills on horses they had to stand on something to mount, without adult supervision. I was last in Price in May with Sylvia and her clan as they decorated graves in the Greek Orthodox cemetery, and I drove with an old east coast friend to see my mother’s grave.
So I took advantage of the situation and named the species after Zella Guymon Dewey (her autobio is at https://docs.google.com/document/d/1T50WOdhu2S2FJEAVcAUDQs3Y1XVHJ9Yv). All the more so because near the end of WW 2 her husband Bill Dewey moved most of the family to the Wash DC area where Gilmore had just placed the future U. z. in the Smithsonian. I lived only a block or a few from them when a little kid. My grandmother was a grand old lady (buried in Arlington National Cemetery with her husband in 2002 by a military guard), LDS but not pushy about it (and she was addicted to Lipton tea, which got her in trouble with church authorities in her 70s), very nice, rather quiet (but apparently she, including with sister Beth, could use spicy language when they thought they were alone!), took me and some cousins to see A Hard Day’s Night in 1964.
And few dinosaurs have been named after women, so making a little correction to that.
Had I looked into it I could have done the taxonomic separation a good while ago. But I probably would not have thought to name it after my GM and her family (which is why it is not just zellae), and the Ute peoples of the region (and I should have named Dakotadon Lakotadon, and Giraffatitan Twigatitan, you can figure that one out). At 18 letters zellaguymondeweyae is tied with three others for the dinosaur species name length record. Of course having started the titan ending for sauropod genus name endings trend, I had to continue that;)
This is the third Smithsonian specimen I have been involved in designating a type – A. fragilis neotype (with Ken C. via ICZN), T. regina holotype. How these are all going to be fit into their little type collection space on the 3rd floor I do not know (in-joke, and U. z. specimen is in storage in Suitland MD facility and others are on display;).
So now Utetitan zellaguymondeweyae is official, not just in the field guides..
GSPaul
Guy Leahy
Oct 9, 2025, 12:57:28 AM (10 days ago) Oct 9
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Several years ago I was at the Tucson Gem, Mineral and Fossil Showcase. One dealer I spoke with specialized in Texas fossils.
He showed me a complete femur of a sauropod which he stated was from the upper Aguja.
Bill Parker
Oct 9, 2025, 1:15:17 AM (10 days ago) Oct 9
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I visited the type locality in the 90s when I was working as the forest paleontologist. There was still some good bone at the site. I also thought it was in the very top of the Price River rather than in the North Horn. Haven’t made it back, but I also have a personal connection to Joes Valley. It’s where I met my wife while she was working with the University of Utah group.
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Tim Williams
Oct 9, 2025, 3:20:30 AM (10 days ago) Oct 9
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Thanks for the familial background - I really like the name _Utetitan zellaguymondeweyae_. It's great that _Alamosaurus sanjuanensis_ is being sorted out - it has tended to be used as a taxonomic wastebasket.
The new Utetitaninae could benefit from a phylogenetic definition - one that mentions this subfamily includes _Utetitan_ but not _Saltasaurus_ or _Opisthocoelicaudia_.
On this: "Probably deposited over a short period of time, the thin Naashoibito section of the lower Ojo Alamo Formation in northwestern New Mexico preserved the _A. sanjuanensis_ types and numerous other specimens. The absence of lambeosaurine hadrosaur fossils precludes a late Maastrichtian age as explained by Jasinski et al. (2011)."
There might be a lambeosaurine from the Naashoibito Member of the Ojo Alamo Formation:
Sullivan, R.M., Jasinski, S.E., Guenther, M., and Lucas, S.G. (2011). The first lambeosaurin (Dinosauria, Hadrosauridae, Lambeosaurinae) from the Upper Cretaceous Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico. Sullivan et al. (Eds), 2011, Fossil Record 3. New Mexico Museum of Natural History and Science, Bulletin 53: 405-417.
https://www.researchgate.net/publication/266459570_The_first_lambeosaurin_Dinosauria_Hadrosauridae_Lambeosaurinae_from_the_Upper_Cretaceous_Ojo_Alamo_Formation_Naashoibito_Member_San_Juan_Basin_New_Mexico
https://www.researchgate.net/publication/266459570_The_first_lambeosaurin_Dinosauria_Hadrosauridae_Lambeosaurinae_from_the_Upper_Cretaceous_Ojo_Alamo_Formation_Naashoibito_Member_San_Juan_Basin_New_Mexico
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Gregory Paul
Oct 9, 2025, 7:57:42 AM (10 days ago) Oct 9
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The late Cretaceous SW sediments are full of titanosaur femora and other remains that are often not collected.
GSPaul
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Gregory Paul
Oct 9, 2025, 8:06:21 AM (10 days ago) Oct 9
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The Utetitan holotype is from the lower North Horn Formation at the SE corner of Joe's Valley. As per Zella's autobio, the LDS townsfolk east of the Wasatch Plateau used to do a summer symbolic pioneer wagon train expedition across the hills through Joes Valley to visit the Manti Temple to the west. How they did that back in the day though the canyons is not obvious. In WW2 one of my uncles in the summer would with fellow preteens take horses for a week into the valley and camp and fish. They had to stand on things to get on the horses. No adult supervision, those were different times. At the end of the autobio is a photo of me and Bakker in the North Horn taken in 1978 when we were there briefly.
GSPaul
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Gregory Paul
Oct 9, 2025, 8:10:14 AM (10 days ago) Oct 9
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The entire phylogeny of titanosaurs is a mess. In part because so many remains are fragmentary. That includes whether the utetitans are from Asia or S America, of which the latter seems much more likely. I stayed away from the phylogeny problem which may not be resolvable.
GSPaul
Richard W. Travsky
Oct 9, 2025, 1:11:48 PM (10 days ago) Oct 9
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Bummer. Log in required.
John D'Angelo
Oct 9, 2025, 3:55:37 PM (10 days ago) Oct 9
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The way I see it, there are four possibilities, broadly speaking, for the evolutionary history of the Alamosaurus complex:
1) The titanosaurs from the Maastrichtian of North America represent a single species, Alamosaurus sanjuanensis.
2) The titanosaurs from the Maastrichtian of North America represent a single lineage that underwent anagensis. In this scenario, it is probably preferable to recognize multiple species within a single genus, Alamosaurus. 3) The titanosaurs from the Maastrichtian of North America represent a single clade that underwent cladogenesis. This scenario is compatible with retaining all Maastrichtian North American titanosaurs in Alamosaurus, but a case could be made for recognizing multiple genera if clear subclades can be recognized.
4) The titanosaurs from the Maastrichtian of North America are not monophyletic and represent multiple dispersal events of separate titanosaur clades into North America. This scenario would almost certainly require the recognition of multiple titanosaur genera in the Maastrichtian of North America.
If these four hypotheses are equally consistent with the evidence, scenario 1 is the most parsimonious. So what does the evidence say?
This paper favors scenarios 2 and 3. Neither of these scenarios provides concrete reason to reject the use of the genus Alamosaurus for all Maastrichtian North American titanosaurs, and the lack of evidence against scenario 2 means splitting Alamosaurus into multiple genera might unnecessarily turn Alamosaurus from a monophyletic genus into a paraphyletic one. Furthermore, I think the widespread historical usage of the name Alamosaurus for the clade Paul calls Utetitaninae favors continued usage of Alamosaurus sensu lato unless more evidence mounts that readily-distinguishable subclades exist that warrant recognition as distinct genera.
I’m not a stratigrapher, but it seems to me like the age constraints on Alamosaurus sensu lato are not terribly strong; while the type specimens could be four million years apart (as Paul suggests in the paper), the error bars appear to be compatible with them being only about one or two million years apart. Two million years is a fairly long time for a species of megafauna to exist, but certainly within the realm of possibility (for comparison, Mammuthus meridionalis existed for between one and two million years). So I don’t think there’s much a priori reason to assume there must have been more than one species. That said, since Paul has provided several characters that apparently distinguish the two species, I am happy with provisionally accepting both Alamosaurus sanjuanensis and Alamosaurus zellaguymondeweyae as a valid species, unless further study shows the differences fall within the scope of individual variation or taphonomy.
On that note, hearing about the review history helped me understand why the Camarasaurus example was used in the paper. However, I somewhat disagree with the notion that "If divergence in the North American titanosaur scapulae is greater than in C. supremus, especially from specimens from differing stratigraphic levels, then that is evidence they do not represent a united taxon." All of the C. supremus scapulae in question are from a single population (and are quite possibly from closely-related individuals) while USNM 10486 and USNM 15560 are not. So the variation in the C. supremus sample represents a minimum of intraspecific variation, not a maximum.
I think we can agree that there’s still more work that needs to be done before we can say that the Alamosaurus complex has been sorted out. And far, far more work that needs to be done before we can say titanosaur phylogeny has been sorted out. On that note, I think giving Utetitaninae a phylogenetic definition would be premature—titanosaur taxonomy has already been sufficiently verschlimmbessert by poorly-defined names such as Rinconsauria, which could contain anywhere from two species to nearly all of Titanosauria, or Aeolosaurini, which has two competing definitions, both of which often fail to correspond well to the clade of Aeolosaurus-like taxa that are consistently recovered close to Aeolosaurus in phylogenetic analyses.
I'm strongly inclined to favor a South American origin for Alamosaurus. It's fairly abundant in southern Laramidia and unknown from the northern half of the landmass, which is exactly the opposite of the distribution you'd expect if it came from Asia, and off the top of my head, I can't think of any phylogenetic analysis that has ever recovered Alamosaurus as sister to an Asian sauropod while adequately sampling possible South American relatives of Alamosaurus such as Pellegrinisaurus.
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Tyler Greenfield
Oct 9, 2025, 4:09:54 PM (10 days ago) Oct 9
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Since the paper doesn't say, what family is Utetitaninae intended to be a subfamily of? If it isn't intended to belong to any family, then it needs to be raised to the rank of family itself.
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Franco Sancarlo
Oct 9, 2025, 4:12:15 PM (10 days ago) Oct 9
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I personally think that using mammals as an example is not correct, mammals sometimes are known for having a very low genetic variability and a hight level of embreeding (eg Panthera) so are not good example. Plus the paper give proof that in fact herbivore dinosaur turn over in a very fast time quoting: "Evidence has grown that herbivorous dinosaur species were prone to turning over rapidly, with species typically not lasting more than a few hundreds of thousands of years (Ryan and Evans, 2005; Paul, 2006, 2016, 2024, in press; Gates, 2012; Scannella et al., 2014; Tschopp et al., 2015; Mallon, 2017, 2019)". So personally I think that Utetitan is a valid genus
Gregory Paul
Oct 9, 2025, 4:58:21 PM (10 days ago) Oct 9
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A reviewer raised the below issue, which I then addressed with a brief comment in the text. Problem is that general titanosaur phylogeny and above genus level taxonomy is a snake pit. Note that Alamosaurus has been placed in Opisthocoelicaudinae within Saltasauridae, incl in its Wikipedia entry. That is extremely implausible, but there is no viable alternative family scheme on hand. Being a fairly sane and rational person who wants to stay that way, and with modest knowledge of titanosaur anatomy and so forth, I am not going to touch that, others can work on that big problem. At the same time, Alamo and Ute have similarities and probably form a regional mini-clade, and in that case I wanted to put them in a subfamily -- a family is not warranted on grounds of limited diversity -- named after the more completely known taxon while I had the opportunity. So that is the suboptimal sub/family situation we are in.
I see that Wikipedia got an entry on the genus up pronto, and mention it in the Alamosaurus entry, which is a good thing. The later should go further on how most or all the latest Maastrichtian SW USA titanosaur material, incl from TX, is probably Utetitan. And the Perot Museum mount is a Utetitan and should be labeled such -- rather than named after that AZ beast. A. sanjuanensis, which is close to a nomen dubium, is sharply limited in remains that can be confidently be assigned to it, and should be considered a minor taxon until more mid-Maastrichtian remains fill it out.
GSPaul
Tyler Greenfield
Oct 9, 2025, 5:15:49 PM (10 days ago) Oct 9
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That is simply not how family-level taxonomy works. A subfamily has to be placed within a family, as it is inherently a nested rank (hence "sub-" in the name). If a subfamily cannot be placed within a family, then it has to be raised to the rank of family. Regarding phylogenetic instability, it would have been more advisable to either name an unranked clade or not name one at all (and I tend to favor the latter).
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Gregory Paul
Oct 9, 2025, 6:27:46 PM (10 days ago) Oct 9
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1) Is not viable because the apparent differences between the shoulder blades as well as the ischia. And only elements from the lower lower Ojo Alamo can be placed with some confidence in A. s., so there is a hefty time gap between the two holotypes.
2) This is plausible, but inferior because the differences are too large to be readily accommodated in one genus. I could not force them into one. And I think that Centrosaurus includes Styracosaurus, Coronosaurus, Rubeosaurus, Einiosaurus, Pachyrhinosaurus..... Hypacrosaurus includes Corythosaurus, Lambeosaurus.....
3) This as per the Goldilocks principle is just right.
4) Not impossible but highly improbable, and there is no evidence for it with the two taxa not being anatomically divergent at the family level.
One reason I did this was to shake people out of assuming all the SW USA titanosaur fossils are one taxon that can be cladistically scored as such. Now folks will have to pay more attention to the substantial differences between the specimens.
GSPaul
John D'Angelo
Oct 9, 2025, 8:31:24 PM (10 days ago) Oct 9
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Tyler, I'm not familiar with what ICZN article says that subfamilies must be assigned to a family—surely a subfamily could be considered incertae sedis between two different families? But, as I said earlier, I think neither a subfamily nor unranked clade was necessary, as there's already a well-established name in widespread usage for the clade of North American titanosaurs: Alamosaurus.
Franco, you're missing my point. I'm not saying that sauropod species necessarily lasted as long as Mammuthus meridionalis, only that there's not enough evidence to rule out the possibility a priori. We can't necessarily assume that the turnover rates observed in ceratopsids and hadrosaurs were typical of sauropods either. So I don't think the sample representing a 3+ million year time span automatically leads to the conclusion that Utetitan is a valid genus, even if it is at least suggestive that more than one species is probably represented in the sample.
Greg, you and I agree that neither scenario 1 nor scenario 4 are supported by the evidence at hand here. I'm listing them for completeness's sake. The difference between scenarios 2 and 3 has nothing to do with how anatomically divergent the species are, but whether anagenesis or cladogenesis occurred, and the available evidence may not be able to distinguish the two scenarios. I think we should recognize that whether to apply a one-genus or two-genus taxonomy is a subjective decision that is informed by but a separate question from what evolutionary scenario occurred. Where my genericometer is calibrated, the differences are enough to tentatively recognize two separate species but not separate genera, so I personally don't think splitting Alamosaurus into multiple genera is an improvement.
Here's a question for you: would you place Pellegrinisaurus in Utetitaninae if it were shown to be the sister taxon of the North American clade?
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Tim Williams
Oct 9, 2025, 8:33:55 PM (10 days ago) Oct 9
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John D'Angelo <dangel...@gmail.com> wrote:
> I think we can agree that there’s still more work that needs to be done before we can say that the Alamosaurus complex has been sorted out. And far,
> far more work that needs to be done before we can say titanosaur phylogeny has been sorted out.
> far more work that needs to be done before we can say titanosaur phylogeny has been sorted out.
Yes, I agree. I really doubt the _Utetitan_ paper will be the last word on sorting out the _Alamosaurus_ complex. But it's a step forward, which is what I intended to convey.
> On that note, I think giving Utetitaninae a phylogenetic
> definition would be premature—titanosaur taxonomy has already been sufficiently verschlimmbessert by poorly-defined names such as Rinconsauria, which
> could contain anywhere from two species to nearly all of Titanosauria, or Aeolosaurini, which has two competing definitions, both of which often fail
> to correspond well to the clade of Aeolosaurus-like taxa that are consistently recovered close to Aeolosaurus in phylogenetic analyses.
> definition would be premature—titanosaur taxonomy has already been sufficiently verschlimmbessert by poorly-defined names such as Rinconsauria, which
> could contain anywhere from two species to nearly all of Titanosauria, or Aeolosaurini, which has two competing definitions, both of which often fail
> to correspond well to the clade of Aeolosaurus-like taxa that are consistently recovered close to Aeolosaurus in phylogenetic analyses.
Here I think the problem is a poor choice of phylogenetic definitions for certain clades. As I suggested earlier for Utetitaninae, a phylogenetic definition that includes negative taxon qualifiers would ensure that this 'subfamily' cannot become too expansive in content (as well as not including name-giving genera for other 'subfamilies').
(I like the term 'verschlimmbessert', btw. First time I've come across it.)
Tyler Greenfield
Oct 9, 2025, 10:09:53 PM (10 days ago) Oct 9
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It is not necessarily an ICZN rule, hence why I said "taxonomy" and not "nomenclature". The Code does dictate the ordering of ranks at the family level (Article 29.2 lists them in order), with families specifically stated to be higher in rank (and have precedence over) subfamilies (Article 35.5). In taxonomy, it is widely accepted that the family is the base rank for classification at the family level. This is in accordance with what is implied by the Code (i.e., they are called 'family-group names' and not 'super- or subfamily-group names'), though not explicitly outlined. Families can thus exist independently, but other family-level ranks are dependent on containing families (superfamilies) or being contained in families (subfamilies, tribes, subtribes). Naming a subfamily without a family goes against the fundamental purpose of this nested hierarchy. You might just as well name the superfamily Utetitanoidea or tribe Utetitanini if you are going to disregard the order. I also disagree with Greg's assertion that Utetitaninae could not be a family for two other reasons: 1) there is no consensus on titanosaur interrelationships and how many genera should usually constitute a family, and 2) even if there was, a duotypic family would still be perfectly reasonable for genera considered a distinct biogeographic lineage. While family-level ranks are not arbitrary relative to each other, they are arbitrary relative to the number of genera and species they each contain.
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Gregory Paul
Oct 10, 2025, 8:28:29 PM (9 days ago) Oct 10
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Maybe, or maybe not. We will need far more fossil data to get a better handle on these issues.
Note that had I named a entire family on just two probably closely related genera that some think are intragenera species (I don't think many think it is just A. san.) then I would have been criticized with justification. At the same time leaving the two taxa just floating out there without a larger clade to contain them is subject to criticism. I did a little compromise merely to deal with the situation. Interesting that it has gotten so much criticism.
GSPaul
Jerry Harris
Oct 11, 2025, 7:23:45 PM (8 days ago) Oct 11
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This, of course, is symptomatic of why Linnaean ranks were jettisoned in modern phylogenetics. There are just no quantifiable, or even definable, degrees of difference between organisms at the "subfamily" and "family" levels—the "inae" suffix doesn't convey anything real about the interrelationships of the taxa within a clade using that suffix that is inherently different than what an "-idae" suffix conveys. They're completely subjective and up to the whim of the taxonomist creating the name. Creating a subfamily without a housing family is strictly necessary housekeeping, I guess, per the ICZN, but ultimately not really meaningful. To avoid this, as others in this thread have noted, it would have been preferable to avoid Linnaean ranks and just create a new clade name, possibly one not involving the old Linnaean suffixes such as "-inae," "-idae," "-ini," etc.—something like "Utetitanosauria" would have been fine and avoided the issue. There's not really a need to attempt to confer via a clade's name any degree of closeness or similarity of the contained taxa the way a "subfamily" rank is supposed to—for example, in some phylogenetic analyses, Rinconsauria is nested within Aeolosaurini, and as far as I know it's not considered problematic that Rinconsauria doesn't have a suffix indicating its "subordinate" position to Aeolosaurini.
Note that I am not at all taking issue here with splitting Alamosaurus specimens into two (or more) genera or species; it's about time someone looked into this issue! And I'm also not doubting that the hypothesis that Alamosaurus and Utetitan are sister taxa to the exclusion of all other known titanosaurians is valid, although it's by no means a given, and it's something that will need testing via phylogenetic analyses in the future. I guess, if anything, I'm taking exception to the retention of the Linnaean rank system in the erection of Utetitaninae.
Tyler Greenfield
Oct 11, 2025, 8:51:06 PM (8 days ago) Oct 11
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I agree with some of what you're saying Jerry, but I do think that family-group names still have their usefulness and need not be abandoned entirely. In other words, there is no inherent contradiction between phylogenetic taxonomy and ranked nomenclature, despite what some phylogeneticists unfortunately think. The fact that family-group names are arbitrary regarding how many genera and species they contain is not actually a negative, but a positive, as it allows for a large degree of taxonomic freedom and consensus building among different researcher communities. In that respect, they are also no more or less arbitrary than names that are above the family level or unranked.
Furthermore, it is beneficial to have a nested hierarchy with clear rules for how the names are formed and used (i.e., regulated priorities and synonymies, stems and suffixes, type genera, authorship attributions, etc.) because it reduces potential nomenclatural confusion. In contrast, names that are above the family level or unranked, which are not governed by the Code, are subject to far more confusion about which names have priority over others, how they should be spelled, how their authorships should be cited, etc.
Also, just a quibble but family-group names are not actually Linnean in the strictest sense. You won't find any families, subfamilies, tribes, etc. in Linnaeus' Systema Naturae because those wouldn't start being used until a decade after his death (as far as I know, Batsch (1788) was the first to name families; see Dubois & Bour (2010)).
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Jerry Harris
Oct 12, 2025, 11:11:40 AM (7 days ago) Oct 12
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I agree that it'd be terrific to have an inherent hierarchy in a taxonomic system, but there are simply too many levels in the hierarchy requiring rank names to make this feasible. I mean, when Homo sapiens is in the genus Homo, the Subtribe Hominina, the Tribe Hominini, The Subfamily Homininae, the Family Hominidae, the Superfamily Hominoidea, the Infraorder Simiiformes, the Suborder Haplorrhini, the Order Primates, the Grandorder Archonta, the Superorder Preptotheria, the Cohort Placentalia, the Supercohort Theria, the Infralegion Tribosphenida, the Sublegion Zatheria, the Legion Cladotheria, the Superlegion Trechnotheria, the Infraclass Holotheria, the Subclass Theriiformes, etc. etc.—that's clumsy and not at all useful in the long run. So many ranks have had to be invented to force things into a Linnaean(-style) framework that it's literally not worth it anymore. Who can remember all that? And when something new is discovered that requires shifting ranks around, who will remember all the new ranks for the existing groups? Especially when assigning a rank to a grouping is arbitrary to begin with—there are no definable criteria for what makes something a Cohort vs. a Superorder, for example. Additionally, what suffixes are useful in indicating that any group pertains to a specific rank when there are so many ranks, and who's going to remember all those?
Ranks have never been about numbers of members: Class Mammalia contains ~4600 species, but Class Insecta contains > 1,000,000 species, and Phylum Placozoa contains four species. Ranks have always been about relative degrees of (anatomical) difference of the members of the group from members of other ranks of the same level, and "degrees of difference" are not actually measurable, quantifiable, or definable, and therefore not replicable—one simply has to trust that someone erecting a group at a specific rank has accurately assessed how different its members are from members of all other groups of that same rank.
Thanks for those references! I was unaware of those and will dive into them!
Milo Gaillard
Oct 12, 2025, 5:34:49 PM (7 days ago) Oct 12
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To John,
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Franco Sancarlo
Oct 12, 2025, 5:55:32 PM (7 days ago) Oct 12
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Using the Utetitan specimen it's a bad idea since this would mean that Utetitan=Alamosaurus but all the specimen of Alamosaurus from the holotype zone would be a new genus. I suggest using another specimen or waiting for a new skeleton.
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Milo Gaillard
Oct 12, 2025, 5:58:13 PM (7 days ago) Oct 12
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Maybe TMM 41541-1 would be better then. I’m honestly not even convinced that “Utetitan” is distinct from Alamosaurus anyway. John went over it better than I could.
Franco Sancarlo
Oct 12, 2025, 6:06:26 PM (7 days ago) Oct 12
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I personally think that are separated genera, the data that the article gives shows that the 2 are very different, plus the time separation mean that we need strong proof that the 2 (counting the found difference ) are the same genus.
Gregory Paul
Oct 12, 2025, 6:13:23 PM (7 days ago) Oct 12
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What? Make the holotype of a new genus the neotype of an earlier named genus that is a near nomen dubium, and can be diagnosed as distinct, and is stratigraphically earlier? I don't think so. I am not sure that is even within ICZN rules. And Alamosaurus is not Iguanodon, Allosaurus, Stegosaurus, or Diplodocus, it is not all that widely known -- and the petition for the last was rejected. Not worth the effort, which I doubt anyone would go to considering that it is likely to be rejected, either upon receipt or later. I for one would oppose such nonsense, as I am pretty sure will others. What may be a good idea is that if a nicely preserved lower Ojo Alamo fossil includes a scapula that is very similar to the Alamosaurus holotype, to make the new specimen a neotype of the taxon. Sort of what happened with Allosaurus. I would likely to support that, but such is not likely to happen in my lifespan.
It is odd that while utetitan remains are common in the SW Maastrichtian, not much in the way of good skeletons. Unlike the Morrison where you get lots of nice sauropods, and many other formations.
GSPaul
Milo Gaillard
Oct 12, 2025, 6:13:30 PM (7 days ago) Oct 12
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Disagree. The differences aren’t very much to me, and two look very similar. The differences could maybe be species level at best (subjective I know), and that’s ignoring other factors (such as taphonomy, or the fact these differences are based on illustrations of the bones and not the actual bones themselves or even pictures of them).
The two could be separated by time, but the ages of the North Horn and Ojo Alamo formations are not very well constrained. I guess North Horn is closer to 66 million years old, but Ojo Alamo’s ages is debated as being anywhere from 70-66 million years old. The same applies to Javenline (poorly constrained age).
So although Utetitan could be distinct from the Alamosaurus of New Mexico, the evidence that Greg Paul presents just isn’t convincing enough for me. And I’ve spoken to several sauropod researchers who find his paper to be problematic.
-Milo
Milo Gaillard
Oct 12, 2025, 6:21:57 PM (7 days ago) Oct 12
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I’m not even against the idea of abandoning the Alamosaurus name personally. The thing is that Alamosaurus is historically important due to being the first sauropod to be named in North America. Furthermore, many sauropod papers over the past several decades have treated it as valid, in the literature. I personally think that abandoning the name would probably cause nomenclatural confusion, and even if Alamosaurus does have an undiagnostic holotype, I think people would still continue to use the name anyway.
Carcharodontosaurus is about as widely known as Alamosaurus. Its holotype is a pair of undiagnostic teeth from the Continental intercalaire of Algeria (a formation with a badly constrained age that could be anywhere from Albian to Cenomanian). A neotype from the Moroccan Kem Kem beds of the Cenomanian was still erected for it, despite not even being from the same country as the holotype. Guess what, it’s still treated as valid to this day. Everyone’s fine with neotype Carchcarodontosuarus, even though it has every reason to not be a neotype. And I agree with them. There’s no need for a name change with Carcharodontosaurus.
I don’t see why Alamosaurus needs a name change either.
-Milo
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On Oct 12, 2025, at 15:13, 'Gregory Paul' via Dinosaur Mailing Group <DinosaurMa...@googlegroups.com> wrote:
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Ethan Schoales
Oct 12, 2025, 6:26:05 PM (7 days ago) Oct 12
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Indeed, please don’t force us to abandon another long-established name.
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Jerry Harris
Oct 12, 2025, 6:55:02 PM (7 days ago) Oct 12
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I haven't seen (or can't find) full papers detailing ages, but some abstracts, anyway, suggest radiometric late Maastrichtian and earliest Paleocene ages for the Naashoibito/Ojo Alamo, e.g. Mason et al. (2013), so I'd say it's on its way to being better constrained. The age of the Javelina and Black Peaks formations in Texas was addressed nicely by Lehman et al. (2022). I'm not aware of any recent attempts to radiometrically date the North Horn Formation, but the biostratigraphy certainly points to at least a partly late Maastrichtian age (e.g., Cifelli et al. (1999)).
Milo Gaillard
Oct 12, 2025, 7:31:47 PM (7 days ago) Oct 12
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So all three are late Maastrichtian. That’s consistent with what I understood about them being roughly coeval.
Btw, I’m sure that there’s more taxa than just Alamosaurus sanjuanensis in all of the Maastrichtian sauropod fossils. No way all of them represent just a single taxon. I suspect overlumping, and this is shared by other sauropod workers.
It’s just that Greg Paul’s way of doing so is weak, imo.
-Milo
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On Oct 12, 2025, at 15:55, Jerry Harris <dino...@gmail.com> wrote:
I haven't seen (or can't find) full papers detailing ages, but some abstracts, anyway, suggest radiometric late Maastrichtian and earliest Paleocene ages for the Naashoibito/Ojo Alamo, e.g. Mason et al. (2013), so I'd say it's on its way to being better constrained. The age of the Javelina and Black Peaks formations in Texas was addressed nicely by Lehman et al. (2022). I'm not aware of any recent attempts to radiometrically date the North Horn Formation, but the biostratigraphy certainly points to at least a partly late Maastrichtian age (e.g., Cifelli et al. (1999)).
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Gregory Paul
Oct 12, 2025, 7:49:21 PM (7 days ago) Oct 12
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My, folks are getting quite worked up about my little titanosaur paper.
Now, now, no need to get panicky, like the folks left of the Titanic after the boats were gone (would not have made much diff had they had enough for all, they did not have time to launch more than what they had, but I digress).
A. san. is not a junior synonym of anything. Cannot be killed off. It is the only name currently applicable for titanosaurs from the lowest most Ojo Alamo. At same time, the only element that can be definitely assigned to the taxon is the holotype scapula (much as the only specimen that at this time definitely is Nanotyrannus is the original skull as explained in my Mesozoic paper). Presumably some happy day a better skeleton will be found that if can be assigned to the taxon, can be designated the neotype if people so choose. The caveat is there is a need to be careful, in some formations titanosaur taxa are a dime a dozen and that could be true for the lower OA.
I of course, preferring being a genus lumper when I can get away with it, tried to pound U. zella. into Alamosaurus. But it would not fit thus Utetitan. Do pay attention to the NH versus the OA ischia, they are very different (Fig. 1B). Supporting the generic distinction is how the U. z. scapula and juvenile BIBE 15560 from TX are dead ringers for one another (the reviewers wouldn't let me use that phrase, party poopers:( and therefore equally different from A. s. (FIg. 1A). Classic evidence the divergence is the real deal.
Remember that the lowermost OA has lambeosaurines in it, and hence cannot be late Maastrichtian, this has been known for some time now. Ergo it is not nearly as young as the lower NH (most of that formation is Paleocene). I do note that the Tyrannosaurus remains found near the U. z. holotype are not definitive age indicators because the taxon may extend much earlier than the late Maastrichtian.
GSPaul
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Gregory Paul
Oct 12, 2025, 7:52:08 PM (7 days ago) Oct 12
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Nope, as published many moons ago there are lambeosaurines at the same level of the lowermost Ojo Alamo that A. san. comes from, so it is not late Maastrichtian. That M seems to not know that indicates this analysis is - unlike my detailed paper -- what is the word I am looking for. oh yes -- weak.
GSPaul
Sean McKelvey
Oct 12, 2025, 8:07:57 PM (7 days ago) Oct 12
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Yeah, can you please stop comparing people disagreeing with your papers to historical disasters or tragic events? Bad taste in my honest opinion.
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Sean McKelvey
Oct 12, 2025, 8:15:58 PM (7 days ago) Oct 12
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"That M seems to not know that indicates this analysis is - unlike my
detailed paper -- what is the word I am looking for. oh yes -- weak".
Real mature Greg, very professional.
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The Dinosaur Heretic
Oct 12, 2025, 8:18:59 PM (7 days ago) Oct 12
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Is there a ZooBank ID registered for this publication or does the third edition of the Princeton Field Guide to Dinosaurs suffice here (as that was the first mention of Utetitan zellaguymondeweyae)? Was this paper also published in print or just electronically?
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Gregory Paul
Oct 12, 2025, 8:33:14 PM (7 days ago) Oct 12
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I spent a lot of effort producing a detailed peer-reviewed ground breaking study. Only to have the results called weak in a public forum. That when that person for reasons unclear was claiming that the lower OA and NH remains are L Maastrichtian in age, which no one in the literature says they are. If one does not want to have their public statements called weak, then they should not make the charge against a technical paper without backing it up. If one dishes out unjustified criticism at a certain rhetorical level online, then do not be upset when it comes back.
If on the other hand someone points out a boo-boo in one of may papers -- as was done earlier regarding a type sentence in the paper -- then more power to them. Solid criticism is useful criticism.
GSPaul
Gregory Paul
Oct 12, 2025, 8:34:06 PM (7 days ago) Oct 12
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The field guide naming was informal. This journal is also in print.
Sean McKelvey
Oct 12, 2025, 8:37:40 PM (7 days ago) Oct 12
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Right, doesn't explain you comparing this disagreement over results with the Titanic disaster, nor does it justify comparing the lack of acceptance for your Tyrannosaur paper to the Ukraine conflict though, does it?
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Gregory Paul
Oct 12, 2025, 8:46:50 PM (7 days ago) Oct 12
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The post was saying what my paper did not, which is that yet another fairly well known dinosaur name was being sunk. Thus false notions initiate and quickly spread. This happens a lot online, and is a form of panic not justified by the circumstances -- unlike the folks left on the sinking ship. I was nipping this errant belief in the bud by being hard hitting about it, which is sometimes required.
All that is needed to avoid the analogies is to be careful to not make inaccurate statements that need serious calling out.
Criticizing my work is more than fine, as long as one is being accurate to what I have said.
GSPaul
Tim Williams
Oct 12, 2025, 8:49:32 PM (7 days ago) Oct 12
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Okay guys, let's turn down the temperature. This is _Alamosaurus_ we're talking about here, not the Alamo.
Milo Gaillard
Oct 12, 2025, 8:50:11 PM (7 days ago) Oct 12
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Thank you.
Sean McKelvey
Oct 12, 2025, 8:53:02 PM (7 days ago) Oct 12
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Once again, you don't need to then compare that to actual tragic events either ongoing or historical. Is the goal to hit a nerve with people or are you just callous and lacking in empathy? Let's try to keep things professional and adult here, instead of resorting to hyperbole.
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Sean McKelvey
Oct 12, 2025, 8:54:19 PM (7 days ago) Oct 12
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The subfamily should be Alamosaurinae anyway imo. It was named first, and is the more widely known genus.
Milo Gaillard
Oct 12, 2025, 8:57:43 PM (7 days ago) Oct 12
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Tim Williams
Oct 12, 2025, 9:33:40 PM (7 days ago) Oct 12
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Sean McKelvey <smc...@gmail.com> wrote:
> The subfamily should be Alamosaurinae anyway imo. It was named first, and is the more widely known genus.
I disagree. In light of the uncertainty surrounding the validity of _Alamosaurus_, this genus is currently not an ideal choice to name a subfamily-level taxon after. 'Widely known' is not always well-defined scientifically. And when deciding which genus should give its name to a family/subfamily, there is no rule or convention regarding priority.
On the topic of subfamilies more broadly... Coordinated family-level taxa are covered by the ICZN. Thus there needs to be a nested hierarchy for these particular taxa (superfamily, family, subfamily, tribe) as denoted by their respective suffixes (-oidea, -idae, -inae, -ini).
Milo Gaillard
Oct 12, 2025, 9:39:13 PM (7 days ago) Oct 12
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Hi. A friend of mine saw your arguments and decided to respond to you. They asked me to post your response, so here.
Hello all,
As my email account is fairly private, I didn’t want to post this myself, but it felt important
to bring it up so Milo has graciously agreed to post it for me. You say that the Naashoibito
Member (I’m avoiding saying Ojo Alamo here as whether the member is actually OA is
controversial, though to me it makes sense) cannot be Late Maastrichtian as there are
lambeosaurin fossils present within. To me this seems like a pretty flimsy argument. The
presence of a single clade, one that was still around barely 3 mya prior and existed for, correct
me if I’m wrong, over 20 my, seems fairly reasonable all things considered. Especially in such a
poorly sampled area. Frankly, if lambeosaurines made it to the Late Maast, I’d expect it to be
here. Additionally, Jerry Harris already posted an abstract detailing new ash layer dating that
pretty strongly constrains it to the latest Maast, specifically no older than 66.5±0.2 mya. (Mason
et. al. 2013) Now I will concede this is just an abstract, but it really wasn’t that hard (a 15 second
Google Scholar search) to find a paper from 2020 that directly posits a Late Maast age for the
Naashoibito Member based both on mammalian faunas and chemical and geological analyses.
To quote the paper directly; “The mammalian faunas of the Naashoibito Member correlate to the
Lancian Land Mammal Age, which suggests a late Maastrichtian age (Williamson and Weil,
2008a). Paleobotanical analyses on the megaflora and pollen indicates that the Ojo Alamo
Sandstone is earliest Paleocene in age and is correlated with palynostratigraphic zones P1 or
P2 (Anderson, 1959; Nichols, 2003; Williamson et al., 2008; Flynn and Peppe, 2019). Recent
detrital sanidine and paleomagnetic work has constrained the Naashoibito Member to the latest
Maastrichtian, which indicates that the K–Pg boundary is represented by the unconformity
between the Naashoibito Member and the Ojo Alamo Sandstone (Peppe et al., 2013; Flynn et
al., 2019). These data, coupled with previous sedimentological analyses, demonstrate that the
Naashoibito Member is late Maastrichtian in age and the Ojo Alamo Sandstone is early
Paleocene in age with an erosive unconformity, that cuts out the Cretaceous–Paleogene
boundary, separating the two units.
” (Flynn et. al. 2020) To me this seems like much stronger
evidence than just the presence of a couple of lambeosaur bones, and the more parsimonious
assumption would be that lambeosaurs simply made it longer than previously thought. I have
thoughts on other aspects of the paper but as I’m nowhere near a sauropod expert I’ll leave it at
this
TL;DR: Naashoibito member is late Maastrichtian in age. Using lambeosaurine fossils as an argument against it is circular reasoning.
-Milo
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Milo Gaillard
Oct 12, 2025, 10:00:15 PM (7 days ago) Oct 12
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To Tim,
I don’t need Alamosaurus to have a clade named after it. Regarding its validity though, I do think that something akin to a neotype would be the best and most viable way to deal with this taxonomic uncertainty. Here’s an argument that I’m copying and pasting here to explain why.
I’m not even against the idea of abandoning the Alamosaurus name personally. The thing is that Alamosaurus is historically important due to being the first sauropod to be named in North America. Furthermore, many sauropod papers over the past several decades have treated it as valid, in the literature. I personally think that abandoning the name would probably cause nomenclatural confusion, and even if Alamosaurus does have an undiagnostic holotype, I think people would still continue to use the name anyway.
Carcharodontosaurus is about as widely known as Alamosaurus. Its holotype is a pair of undiagnostic teeth from the Continental intercalaire of Algeria (a formation with a badly constrained age that could be anywhere from Albian to Cenomanian). A neotype from the Moroccan Kem Kem beds of the Cenomanian was still erected for it, despite not even being from the same country as the holotype. Guess what, it’s still treated as valid to this day. Everyone’s fine with neotype Carchcarodontosuarus, even though it has every reason to not be a neotype. And I agree with them. There’s no need for a name change with Carcharodontosaurus.
I don’t see why Alamosaurus needs a name change either.
-Milo
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Sean McKelvey
Oct 12, 2025, 10:15:06 PM (7 days ago) Oct 12
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"I disagree. In light of the
uncertainty surrounding the validity of _Alamosaurus_, this genus is
currently not an ideal choice to name a subfamily-level taxon after.
'Widely known' is not always well-defined scientifically. And when
deciding which genus should give its name to a family/subfamily, there
is no rule or convention regarding priority."
Uncertainty from whom? This one paper? To the best of my knowledge Alamosaurus is still considered a valid genus by most researchers. I am aware that there are really no rules around priority here, I just don't think it's reasonable to name a subfamily containing an established, and more well known taxa, after a newly described taxa. To me that stinks more of egotism than actual scientific validity. To me it would be the equivalent of attempting to rename Tyrannosaurinae to Zuchengtyrannidae.
It's things like this that hamper efforts for public engagement with this subject. imho.
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Tim Williams
Oct 12, 2025, 10:22:26 PM (7 days ago) Oct 12
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> I’m not even against the idea of abandoning the Alamosaurus name personally. The thing is that Alamosaurus is historically important due to being the first sauropod to be named in North America.
I would very much prefer to keep the genus _Alamosaurus_ alive, for the reasons you give - even if it means a neotype at some point. Unfortunately (as GSP noted) a better specimen is probably required than is currently available. But I agree that a neotype is a viable option in principle.
> Furthermore, many sauropod papers over the past several decades have treated it as valid, in the literature. I personally think that abandoning the name would probably cause nomenclatural confusion, and even if Alamosaurus
> does have an undiagnostic holotype, I think people would still continue to use the name anyway.
I'm not so sure. When _Titanosaurus_ was declared a nomen dubium back in 2003, the genus soon sank without a trace. Up to that point, _Titanosaurus_ was a widely known and time-honored name, as well as the name-giving genus for multiple higher-level clades. Now _Titanosaurus_ is effectively dead. The same fate could ultimately await poor _Alamosaurus_.
> Carcharodontosaurus is about as widely known as Alamosaurus. Its holotype is a pair of undiagnostic teeth from the Continental intercalaire of Algeria (a formation with a badly constrained age that could be anywhere from Albian to
> Cenomanian). A neotype from the Moroccan Kem Kem beds of the Cenomanian was still erected for it, despite not even being from the same country as the holotype.
This is not a deal-breaker. The neotype for _Iguanodon_ is not from England.
Grant Hurlburt
Oct 12, 2025, 10:34:48 PM (6 days ago) Oct 12
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I dont care passionately either way but it is not necessary to have all those "neo-Linnean" layers in most cases, especially for a Mesozoic fossil without all the subdivs one finds for the more recent Homo sapiens, whose. Species, Genus, Subfam., Fam., Order, &Class are all that are needed, espec. for Alamosaurus, for which Order & class exist, & so prob do some other subdivs. above Family (with ref to:" I mean, when Homo sapiens is in the genus Homo, the Subtribe Hominina, the Tribe Hominini, The Subfamily Homininae, the Family Hominidae, the Superfamily Hominoidea, the Infraorder Simiiformes, the Suborder Haplorrhini, the Order Primates, the Grandorder Archonta, the Superorder Preptotheria, the Cohort Placentalia, the Supercohort Theria, the Infralegion Tribosphenida, the Sublegion Zatheria, the Legion Cladotheria, the Superlegion Trechnotheria, the Infraclass Holotheria, the Subclass Theriiformes, etc. etc.").
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Grant Hurlburt
Milo Gaillard
Oct 12, 2025, 10:35:42 PM (6 days ago) Oct 12
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We could use Utetitan and sink that into Alamosaurus (especially since the differences that Paul points out are not convincing enough imo, for multiple reasons). Alternatively, we could use one of the Texas specimens as a candidate. TMM 41541-1 is a good one.
-Milo
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Sean McKelvey
Oct 12, 2025, 10:43:14 PM (6 days ago) Oct 12
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"
We could use Utetitan and sink that into Alamosaurus (especially since
the differences that Paul points out are not convincing enough imo, for
multiple reasons). Alternatively, we could use one of the Texas
specimens as a candidate. TMM 41541-1 is a good one."
I agree. Nothing in the paper really convinces me beyond a shadow of a doubt that we're looking at anything more than species level distinction. Naming an entirely new genus is jumping the gun imo.
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Milo Gaillard
Oct 12, 2025, 10:55:38 PM (6 days ago) Oct 12
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Agreed. Even if we say that the Alamosaurus holotype is diagnostic (I doubt scapulae alone are diagnostic enough), the differences are only species level at best. And this isn’t even factoring in the big issue with his differences: they are not based on the bones themselves or even pictures, they’re based on his illustrations. His interpretations.
That could easily exaggerate the differences between the two scapulae.
-Milo
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Milo Gaillard
Oct 12, 2025, 10:59:05 PM (6 days ago) Oct 12
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So I agree with sinking Utetitan, considering that it was (and probably still is) the most complete Alamosaurus specimen.
-Milo
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Tim Williams
Oct 13, 2025, 1:04:01 AM (6 days ago) Oct 13
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Milo Gaillard <miloga...@gmail.com> wrote:
> We could use Utetitan and sink that into Alamosaurus (especially since the differences that Paul points out are not convincing enough imo, for multiple reasons). Alternatively, we could use one of the Texas specimens as a candidate.
> TMM 41541-1 is a good one.
Yes, TMM 41541-1 is based on a decent specimen (partial skeleton) from Upper Javelina Formation, Big Bend National Park. So not from the same horizon as the _Alamosaurus_ holotype. Again, not a deal-breaker. But any petition to the ICZN to nominate TMM 41541-1 as the neotype may get knocked back by the Commission for this reason.
Sean McKelvey <smc...@gmail.com> wrote:
> Uncertainty from whom? This one paper? To the best of my knowledge Alamosaurus is still considered a valid genus by most researchers.
> Uncertainty from whom? This one paper? To the best of my knowledge Alamosaurus is still considered a valid genus by most researchers.
Note that Lucas and Sullivan (2000) declared _Alamosaurus sanjianensis_ to be a nomen dubium, because in their view the holotype scapulae couldn't easily be distinguished from the scapulae of certain South American titanosaurids.
The genus _Alamosaurus_ has traditionally been regarded as valid based on the hypodigm (totality of assigned material) - and *despite* the possibly non-diagnostic nature of the holotype. Lucas and Sullivan (2000) also raised the prospect of designating a neotype at some point in the future: "Certainly one, and possibly more, titanosaurid taxa are represented by the thus-far collected specimens of _Alamosaurus_, but
the name _A. sanjuanensis_ is based on an inadequate holotype. If
and when a potentially diagnostic specimen is discovered, we
believe it will be useful (by preserving longstanding usage) to set
aside the holotype and designate a neotype."
So the suggestion of an _Alamosaurus_ neotype is not new.
Note also that an articulated cervical series (BIBE 45854; cervicals #6-14) referred to _Alamosaurus_ by Tykoski and Firillo (2017), was found by Navarro et al. (2022) to belong to Lognkosauria, whereas what the latter study called _Alamosaurus_ was recovered inside Saltasaurinae - so very different parts of the titanosaur tree. I only mention this to highlight that the hypodigm traditionally used to uphold the validity of _Alamosaurus_ was looking shaky before GSP and _Utetitan_came along.
> I am aware that there are really no rules around priority here, I just don't think it's reasonable to name a subfamily containing an established, and more well known taxa, after a newly described taxa. To me that stinks more of egotism
> than actual scientific validity. To me it would be the equivalent of attempting to rename Tyrannosaurinae to Zuchengtyrannidae.
I don't think this analogy is apt. GSP did not propose that a taxon be renamed. And it might be the case that Utetitaninae is never used in the foreseeable future, despite being an available taxon name.
> It's things like this that hamper efforts for public engagement with this subject. imho.
Opinion noted.
Sean McKelvey
Oct 13, 2025, 2:12:50 AM (6 days ago) Oct 13
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>
Note that Lucas and Sullivan (2000) declared _Alamosaurus sanjianensis_
to be a nomen dubium, because in their view the holotype scapulae
couldn't easily be distinguished from the scapulae of certain South
American titanosaurids.
While that may be the case, it was found in North America, so unless the remains belong to a genus of South American Titanosaurid that was present in both regions, the scapula almost certainly belongs to a distinct taxa.
>
Note also that an articulated cervical series (BIBE 45854; cervicals
#6-14) referred to _Alamosaurus_ by Tykoski and Firillo (2017), was
found by Navarro et al. (2022) to belong to Lognkosauria, whereas what
the latter study called _Alamosaurus_ was recovered inside
Saltasaurinae - so very different parts of the titanosaur tree. I only
mention this to highlight that the hypodigm traditionally used to uphold
the validity of _Alamosaurus_ was looking shaky before GSP and
_Utetitan_came along.
I honestly fail to see how the interrelationships of Titanosaurs being messy and difficult to work out = Alamosaurus is invalid.
>
I don't think this analogy is apt. GSP did not propose that a taxon be
renamed. And it might be the case that Utetitaninae is never used in
the foreseeable future, despite being an available taxon name.
The analogy was fine. My point was that I don't see why the subfamily wasn't called Alamosaurinae. Once again, the only justification I can come up with for the desire to name the subfamily Utetitaninae is for the sake of ego or to be contrary to "establishment"
>
Opinion noted.
It is a serious problem though. We are in an age where misinformation can be spread widely and incredibly easily. Not to mention that "anti-science" views and distrust of science as a whole is a growing issue. The fact that taxa are erected, then torn down, then erected again over and over is, from the perspective of a layman, incredibly annoying and frustrating.
I'll leave it at this. This is not the first time GSP has lumped or split taxa, nor will it be the last. But, based on past instances I require more evidence than just a single paper by Paul that suggests a separate genus is present. Honestly, as it stands, I don't think we have enough remains that are complete enough to be making such a call. Just my opinion though.
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Mickey Mortimer
Oct 13, 2025, 3:05:11 AM (6 days ago) Oct 13
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Lucas and Sullivan believed Alamosaurus was a nomen dubium specifically because "it is not so easy to differentiate the holotype scapula of A. sanjuanensis from that of some other titanosaurids, including Laplatasaurus araukanicus (Huene, 1929, pl. 23) and Saltasaurus loricatus (Bonaparte and Powell, 1980, fig. 4; also see McIntosh, 1990, fig. 16.8) (Fig. 3). Indeed, based solely on its holotype scapula, we cannot diagnose Alamosaurus from these two South American titanosaurids." Huene actually shows two different scapulae referred to Laplatasaurus in Plate 23, and neither are currently referred to it (Gallina and Otero, 2015), although the one in Figure 1 is from the type locality (and is what Lucas and Sullivan's bad drawing in their Figure 3 is based on). The latter has (with the scapula held horizontal and having proximodistal and dorsoventral axes) a proximodistally longer ventral glenoid projection, deeper postglenoid concavity, the other one has a less ventrally projected glenoid and angled dorsal scapular edge, and both have a deeper acromion and supraglenoid fossa that extends further distally (these features probably have established names, but I'm not a sauropod worker). So not only are these not assignable to a named genus (though the one in Figure 2 was assigned to cf. Bonitasaura sp. by Gallina and Otero), but both are easily distinguishable from Alamosaurus. In Saltasaurus (better illustrated in Powell, 1992: Figure 28), the glenoid is much thicker proximodistally and angled from the shaft, which is itself much deeper (42% of proximal scapular depth vs. 31%) and has a dorsal bulge in the middle, the acromion is more angled from the shaft and its edge is evenly convex instead of transitioning from concave to convex. The supraglenoid fossa extends further distally like the 'Laplatasaurus' scapulae, and there's a medial process on the dorsal edge of the internal shaft surface not seen in Alamosaurus. So as is often the case with nomen dubium claims, the differences do exist but were not mentioned by the authors. I'd say even restricted to the holotype scapula, Alamosaurus' validity seems justified until someone comes up with a better match than the ones Lucas and Sullivan suggested.
Mickey Mortimer
Tim Williams
Oct 13, 2025, 3:24:44 AM (6 days ago) Oct 13
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Mickey Mortimer <therizino...@gmail.com> wrote:
> I'd say even restricted to the holotype scapula, Alamosaurus' validity seems justified until someone comes up with a better match than the ones Lucas and Sullivan suggested.
Yes, others have interpreted the incomplete scapula (USNM 10846) as diagnostic (e.g., D'Emic et al., 2011).
Sean McKelvey <smc...@gmail.com> wrote:
> While that may be the case, it was found in North America, so unless the remains belong to a genus of South American Titanosaurid that was present in both regions, the scapula almost certainly belongs to a distinct taxa.
As the holotype, the name _Alamosaurus sanjuanensis_ is attached to this scapula (USNM 10846). This alone is the name-bearing specimen. The issue is what other material can be assigned to the same species as this scapula.
> I honestly fail to see how the interrelationships of Titanosaurs being messy and difficult to work out = Alamosaurus is invalid.
My point was that the material assigned to _Alamosaurus_ is messy and difficult to work out. For example, it is possible (though I'm certainly *not* advancing this interpretation) that the cervical series BIBE 45854 belongs to a lognkosaur, and USNM 10846 belongs to a saltasaurine.
If there is multiple titanosaur species represented among the material that has traditionally been labelled "_Alamosaurus_", then it becomes trickier to determine which of this material is assignable to _A. sanjuanensis_.
Sean McKelvey
Oct 13, 2025, 5:29:15 AM (6 days ago) Oct 13
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>
As the holotype, the name _Alamosaurus sanjuanensis_ is attached to this
scapula (USNM 10846). This alone is the name-bearing specimen. The
issue is what other material can be assigned to the same species as this
scapula.
Ah, fair. I seem to have gotten my information crossed at some point. Noted.
>My point was that the material assigned to _Alamosaurus_ is messy and difficult to work out. For example, it is possible (though I'm certainly *not* advancing this interpretation) that the cervical series BIBE 45854 belongs to a lognkosaur, and USNM 10846 belongs to a saltasaurine.
Valid point, I guess my issue hinges around that, if the situation is as messy as previously stated, than it seems a leap to erect a new genus, rather than just something like ident. Eutitanosauria or Lithostrotia. Hopefully more remains and further research can clear this all up.
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Milo Gaillard
Oct 13, 2025, 7:56:46 AM (6 days ago) Oct 13
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Fair point about Carcharodontosaurus. I will say though that even if the two holotype teeth weren’t lost, they would still be undiagnostic.
-Milo
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Milo Gaillard
Oct 13, 2025, 8:05:21 AM (6 days ago) Oct 13
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I’ve spoken to several sauropod researchers myself. They all think that the type is undiagnostic below family level.
I’m sure that there are multiple titanosaur taxa represented by the material that we call Alamosaurus sanjuanensis. However, I also don’t see why we should abandon the Alamosaurus name. Even if Alamosaurus was called a nomen dubium, I’m sure that subsequent papers will just choose to ignore it.
When Troodon became a nomen dubium from 2017-2025, a decent chunk of subsequent papers ignored that and still continued to use Troodon. They did not switch to Stenonychosaurus. The same thing happened with Kronosaurus and Eiectus. Guess what? Subsequent papers ignored that and chose to use Kronosaurus.
I predict that the same thing will happen if someone decides to kill the Alamosaurus name. In fact, Lucas and Sullivan called it a nomen dubium in 2000. Even before D’Emic argued that it was diagnostic in 2011, a good handful of papers still used the name and treated it as it were valid.
-Milo
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Milo Gaillard
Oct 13, 2025, 8:13:27 AM (6 days ago) Oct 13
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I will say that we can still just sink Utetitan into Alamosaurus and make that the Alamosaurus neotype. Although the Texas material has been suggested to be distinct from Alamosaurus, the Utah material has never been suggested to be distinct (tmk anyway) aside from Greg Paul. And the differences that Paul points out are both incredibly unconvincing and based on his illustrations, as opposed to the actual bones themselves.
I agree with you saying that it’s pointless to erect new names, and both Utetitan and the whole “Utetitaninae” nonsense does feel like Paul trying to be all contrarian, so he could boost his ego.
-Milo
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On Oct 13, 2025, at 02:29, Sean McKelvey <smc...@gmail.com> wrote:
Gregory Paul
Oct 13, 2025, 8:13:53 AM (6 days ago) Oct 13
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Ok. We see it again. I get dumped on for my attitude on the paper I busted my butt on -- apparently ironically comparing what was the beginning of over-excitement about the demise of Alamosaurus which I did not demise (similar to how I think many are freaked out about the new Tyrannosaurus species because they think that challenges the existence of T. rex which it does not) to the loss of a ship, which apparently is just not to be allowed on a discussion list. Yeah right.
So below I am accused of being an elderly egotist. The first item is accurate, but the manner it is done is ageist bigotry and should not be seen on the list. The 2nd is just pure slander. Yet no one has objected to those snarky attacks. And there is no "establishment" viewpoint on the matter, no one had put Alamosaurus into a family level clade that contained the SW titanosaurs. So all options were open.
There is no justification for Utetitanae over Alamosaurinae? Using the more complete specimen to designate a subfamily over a single element is a bad choice? Had I done that I would get criticized for having done that. No matter what I did I would have caught it, including not erecting a higher taxon to contain the SW titanosaurs. There is no great solution to this, all options are medicore. And what is the big deal anyhow? Folks use Tyrannosauridae based on excellent remains all the time over Deinodontidae despite the latter having priority.
So I did what seemed best with the limited data on hand and get called old and egotistical for being the first to take an in-depth look at the SW titanosaur problem (while honoring my centurian grandmother and a woman, and the displaced Ute people) and not magically and impossibly making everyone happy all at the same time.
Gosh thanks!
GSPaul
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Gregory Paul
Oct 13, 2025, 8:22:11 AM (6 days ago) Oct 13
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Photos of the bones have already been published and they are all listed in the paper. There was no need to repeat them, anyone can look them up (in any case, an archive search at the Smithsonian failed to find the old originals published by Gilmore). As I explain in the methods, I traced the elements at a large scale so the outlines are precise -- I ahve been doing this for decades, I do not do the sketch art illustrations one sometimes sees. Because the illustrations include bone bits that have since broken off the elements, they are actually more complete than some recently taken and published photos as noted in the paper. And they are too the correct same scale, unlike some recent publications.
GSPaul
Gregory Paul
Oct 13, 2025, 8:32:13 AM (6 days ago) Oct 13
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And I would of course have caught flack for naming a subfamily after a single element that might be a nomen dubium. Duh. There was no optimal choice with the limited remains on hand, and being the first to take a deep dive into the issue I got to choose what genus to use, so I picked the more completely known genus. Nothing wrong with that.
GSPaul
Gregory Paul
Oct 13, 2025, 8:39:58 AM (6 days ago) Oct 13
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To repeat, my paper does not, NOT, sink Alamosaurus. By giving it the first accurate diagnosis, I am actually giving it some support. If in the future the name goes out of use for some reason don't blame me, I did my best to keep it potentially valid. And you have to work at that, the holotype being so close to being a nomen dubium. I was tempted to declare it a ND, but figured what the heck, and it can be easily diagnosed from the two Utetitan scapulae which are so similar to one another.
And the egotism thingy again. At least this one does not get into the age matter. Have we seen such on the dinosaur list before?
GSPaul
Gregory Paul
Oct 13, 2025, 8:45:54 AM (6 days ago) Oct 13
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41541 is just a neck that cannot be cross-compared to other SW titanosaurs. So me thinks it cannot be diagnosed relative to other specimens.
It is easy to make a critical casual assertion, not so much to actually come up with a supporting analysis. If M really thinks 41541 is a good holotype, then please come up with a diagnosis based on it that distinguishes it from other SW titanosaurs. Seriously, that could be interesting. If such cannot be done, then the suggestion was of limited utility.
GSPaul
Milo Gaillard
Oct 13, 2025, 9:22:46 AM (6 days ago) Oct 13
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No, TMM 41541-1 is a partial skeleton. You’re probably getting it mixed with BIBE 45854. https://www.tandfonline.com/doi/full/10.1080/14772019.2016.1183150#d1e1766
-Milo
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On Oct 13, 2025, at 05:45, 'Gregory Paul' via Dinosaur Mailing Group <DinosaurMa...@googlegroups.com> wrote:
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Gregory Paul
Oct 13, 2025, 10:30:17 AM (6 days ago) Oct 13
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Go ahead and diagnosis it to establish a distinctive taxon. Lacks the scapula, apparently.
GSPaul
Sean McKelvey
Oct 13, 2025, 7:03:08 PM (6 days ago) Oct 13
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Get over yourself Greg. People are within their rights to point out what they perceive as flaws with your work, as they are free to make their own assessments about how they feel about you as a person. If you aren't willing to cop flack for your work, you don't need to publish it. If you put something out into the world, people will respond as they see fit.
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Tim Williams
Oct 13, 2025, 7:13:36 PM (6 days ago) Oct 13
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Milo Gaillard <miloga...@gmail.com> wrote:
If the holotype is shown to be non-diagnostic at genus level, then _Alamosaurus_ will be a nomen dubium. It's happened before with _Titanosaurus_. It would have happened to _Cetiosaurus_ as well, had the type species not been changed (by ICZN petition). There's a whole bunch of high-profile genera that would have been regarded as nomina dubia had neotypes not been designated (again via the ICZN) - _Allosaurus_, _Iguanodon_, _Coelophysis_, etc etc.
> Even if Alamosaurus was called a nomen dubium, I’m sure that subsequent papers will just choose to ignore it.
Who's to say? But when GSP says that _A. sanjuanensis_ is "dangerously close to being a nomen dubium", he's not wrong. That's not ego; that's the taxonomic reality. A species is only as good as its holotype, and _A. sanjuanensis_ is hanging by a thread.
> When Troodon became a nomen dubium from 2017-2025, a decent chunk of subsequent papers ignored that and still continued to use Troodon. They did not switch to Stenonychosaurus.
_Troodon_ is perhaps not the best example. The situation is quite complicated (e.g. explained in Varricchio et al. 2025 doi.org/10.1017/jpa.2024.67 ). Varricchio &c make it clear that they want to keep the name _Troodon_ alive, but this requires a neotype to be designated. (This is in the pipeline, according to the aforementioned paper.)
> The same thing happened with Kronosaurus and Eiectus. Guess what? Subsequent papers ignored that and chose to use Kronosaurus.
Yes, but designating a neotype for _Kronosaurus_ is probably still the best option, such as using the _E. longmani_ holotype. This is what Noè & Gómez-Pérez (2021) should have done... as opposed to what they actually did do.
Tim Williams
Oct 13, 2025, 7:49:56 PM (6 days ago) Oct 13
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> So below I am accused of being an elderly egotist. The first item is accurate, but the manner it is done is ageist bigotry and should not be seen on the list. The 2nd is
> just pure slander. Yet no one has objected to those snarky attacks.
> just pure slander. Yet no one has objected to those snarky attacks.
I'm objecting right now. I am going to insist that people NOT express their own assessments about how they feel about you (or anyone else) as a person. This is known as 'ad hominem', and it's outside what is considered acceptable on the DMG. If anyone has any queries or objections, please direct them off-list to me.
> There is no justification for Utetitanae over Alamosaurinae? Using the more complete specimen to designate a subfamily over a single element is a bad choice?
In light of the questionable status of the _Alamosaurus_ holotype, I agree it's a poor choice to name a subfamily after _Alamosaurus_. So no argument from me. Whether a subfamily needed to be erected in the first place is a different matter.
> Folks use Tyrannosauridae based on excellent remains all the time over Deinodontidae despite the latter having priority.
As of 2024, Tyrannosauridae officially has precedence over Deinodontidae (International Commission on Zoological Nomenclature Opinion 2511 / Case 3815)
Gregory Paul
Oct 13, 2025, 7:57:48 PM (6 days ago) Oct 13
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I should have said people used Tyrannosauridae over Deinodontidae informally for decades, before the ICZN tidied things up, bless em.
GSPaul
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Milo Gaillard
Oct 13, 2025, 8:30:49 PM (6 days ago) Oct 13
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Actually, what you said about Alamosaurus is interesting, because it was considered to be a nomen dubium (okay nomen vanum, but that’s essentially the same thing) all the way back in Lucas & Sullivan (2000) (https://www.researchgate.net/publication/285860767_The_sauropod_dinosaur_Alamosaurus_from_the_Upper_Cretaceous_of_the_San_Juan_Basin_New_Mexico).
Yet them calling it an undiagnostic taxon was ignored in subsequent papers. Even before 2011 (where D’Emic somehow found the holotype diagnostic) Alamosaurus was still repeatedly mentioned, treated as valid, had specimens referred to it despite limited diagnostic overlap, and I think may have even been put in phylogenies (not 100% sure about that last bit).
Examples:
https://www.miketaylor.org.uk/dino/pubs/taylor2009/Taylor2009-brachiosaurus-and-giraffatitan.pdf (Taylor puts Alamosaurus in this paper’s phylogeney)
The North Horn T. rex paper treats Alamosaurus as valid.
Milo Gaillard
Oct 13, 2025, 8:33:15 PM (6 days ago) Oct 13
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One more thing. I talked to at least one sauropod researcher about this. He agrees that Alamosaurus should get a neotype.
Sent from my iPhone
On Oct 13, 2025, at 17:30, Milo Gaillard <miloga...@gmail.com> wrote:
Actually, what you said about Alamosaurus is interesting, because it was considered to be a nomen dubium (okay nomen vanum, but that’s essentially the same thing) all the way back in Lucas & Sullivan (2000) (https://www.researchgate.net/publication/285860767_The_sauropod_dinosaur_Alamosaurus_from_the_Upper_Cretaceous_of_the_San_Juan_Basin_New_Mexico).
<North Horn Tyrannosaurus rex.pdf>I could go on.Point is, making Alamosaurus invalid already didn’t work before. People ignored it. Why would it work now?Seriously. That’s why I think a neotype designation is the best option to help these issues, and I think that “Utetitan” is the best candidate for the neotype.Researchers ignore Kronosaurus being a nomen dubium. Researchers also treat Troodon as valid, despite the neotype not even being official.If the researchers chose to ignore Alamosaurus being a nomen dubium, then so be it. It’s just a name after all. I think we can use it for the Utah specimens and Greg Paul trying to name a new genus and species off of it is a mistake.But that’s just my opinion. Hope you understand.-Milo
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Gregory Paul
Oct 13, 2025, 9:11:46 PM (6 days ago) Oct 13
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So go ahead and cite a neotype and diagnose it relative to other SW titanosaurs.
GSPaul
Isaac Wilson
Oct 13, 2025, 9:20:52 PM (6 days ago) Oct 13
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Man, DMG is gettin' sassy.
Let me put on the soundtrack to Disney's Dinosaur and pop some popcorn real quick.
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Mickey Mortimer
Oct 13, 2025, 9:53:31 PM (6 days ago) Oct 13
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Milo Gallaird wrote- "
I’ve spoken to several sauropod researchers myself. They all think that the type is undiagnostic below family level."
"Yet them calling it an undiagnostic taxon was ignored in subsequent papers."
Here's the thing- it's easy to declare a taxon nomen dubium, but most of the time people don't actually put in the work to support it. Lucas and Sullivan even went beyond most workers and listed two other taxa Alamosaurus was supposedly undiagnosable compared to (because if you only have one other taxon, they're synonyms), but as I demonstrated above this is not true. You can even see the differences in their badly drawn Figure 3. So that's why people often ignore such declarations (in addition to splitters vs. lumpers, and I'm a lumper and still think Alamosaurus and Saltasaurus have quite different scapulae). What someone would have to do to defend Lucas and Sullivan's assertion is to demonstrate the Alamosaurus vs. Saltasaurus differences they list are also found in conspecific sauropod individuals, which obviously nobody has done. Indeed, Powell (1992) even uses "Medial prominence is close to the upper edge of the scapula" (translated), which I noted, as a diagnostic character of his Saltasaurinae. But despite being written 8 years after that publication, Lucas and Sullivan (2000) were still depending on Saltasaurus' 1987 original short description (and referencing McIntosh's 1990 redrawing for The Dinosauria, which really isn't something a professional wants to reference The Dinosauria for...). That's probably part of why their nomen dubium assertion was ignored by some- it was outdated before it was written.
"Fair point about Carcharodontosaurus. I will say though that even if the two holotype teeth weren’t lost, they would still be undiagnostic."
Well, maybe. But here again, the authors proposing it didn't put in the work. Brusatte and Sereno (2007) merely wrote "Both teeth ... have pronounced arcuate marginal enamel wrinkles. ... At the time they were originally described, such pronounced marginal enamel wrinkles were unknown elsewhere among theropods. ... We have observed marginal enamel wrinkles of identical form in the broadest crowns of Giganotosaurus carolinii, although they have yet to be figured. ... Thus, there are several problems with the holotypic teeth of Carcharodontosaurus (Megalosaurus) saharicus: ... the diagnostic characters originally cited are no longer diagnostic at the specific or generic level...". So based on one character apparently shared with another taxon, only based on personal observation and not demonstrated in the paper, they declared it a nomen dubium. Maybe there are other characters Deperet and Savornin didn't write about in the 1920s that differ from the mostly undescribed and mostly unillustrated teeth of Giganotosaurus? You can't just take an original diagnosis and say "well, those characters are all shared with other taxa, time to sink it", you have to put in the work yourself to evaluate the existing differences (since no two bones are identical) and show they're at least plausibly individual/positional/ontogenetic/etc. variation. Rauhut actually recently proposed Carcharodontosaurus teeth are distinguishable from Stromer's Tameryraptor, writing "In contrast to SNSB-BSPG 1922 X 46 [Tameryraptor], all preserved maxillary teeth of Carcharodontosaurus saharicus show a more typical backwards curvature with the tip of the tooth positioned over the distal half of the tooth base", and the original Carcharodontosaurus syntypes do match the neotype in this regard. So maybe carcharodontosaurine teeth are diagnostic at lower levels. If someone wants to propose Carcharodontosaurus and Giganotosaurus can't be distinguished dentally, they should take a database of quantitative measurements and characters like Hendrickx's to demonstrate it. Finally, the fact the teeth are lost is part of what makes them less diagnostic because we only have short, outdated descriptions and two views of one tooth and one view of the other. There could have been differences in denticle shape, cross section, enamel texture, etc., but we'll never know unless they are later found.
"Yet them calling it an undiagnostic taxon was ignored in subsequent papers."
Here's the thing- it's easy to declare a taxon nomen dubium, but most of the time people don't actually put in the work to support it. Lucas and Sullivan even went beyond most workers and listed two other taxa Alamosaurus was supposedly undiagnosable compared to (because if you only have one other taxon, they're synonyms), but as I demonstrated above this is not true. You can even see the differences in their badly drawn Figure 3. So that's why people often ignore such declarations (in addition to splitters vs. lumpers, and I'm a lumper and still think Alamosaurus and Saltasaurus have quite different scapulae). What someone would have to do to defend Lucas and Sullivan's assertion is to demonstrate the Alamosaurus vs. Saltasaurus differences they list are also found in conspecific sauropod individuals, which obviously nobody has done. Indeed, Powell (1992) even uses "Medial prominence is close to the upper edge of the scapula" (translated), which I noted, as a diagnostic character of his Saltasaurinae. But despite being written 8 years after that publication, Lucas and Sullivan (2000) were still depending on Saltasaurus' 1987 original short description (and referencing McIntosh's 1990 redrawing for The Dinosauria, which really isn't something a professional wants to reference The Dinosauria for...). That's probably part of why their nomen dubium assertion was ignored by some- it was outdated before it was written.
"Fair point about Carcharodontosaurus. I will say though that even if the two holotype teeth weren’t lost, they would still be undiagnostic."
Well, maybe. But here again, the authors proposing it didn't put in the work. Brusatte and Sereno (2007) merely wrote "Both teeth ... have pronounced arcuate marginal enamel wrinkles. ... At the time they were originally described, such pronounced marginal enamel wrinkles were unknown elsewhere among theropods. ... We have observed marginal enamel wrinkles of identical form in the broadest crowns of Giganotosaurus carolinii, although they have yet to be figured. ... Thus, there are several problems with the holotypic teeth of Carcharodontosaurus (Megalosaurus) saharicus: ... the diagnostic characters originally cited are no longer diagnostic at the specific or generic level...". So based on one character apparently shared with another taxon, only based on personal observation and not demonstrated in the paper, they declared it a nomen dubium. Maybe there are other characters Deperet and Savornin didn't write about in the 1920s that differ from the mostly undescribed and mostly unillustrated teeth of Giganotosaurus? You can't just take an original diagnosis and say "well, those characters are all shared with other taxa, time to sink it", you have to put in the work yourself to evaluate the existing differences (since no two bones are identical) and show they're at least plausibly individual/positional/ontogenetic/etc. variation. Rauhut actually recently proposed Carcharodontosaurus teeth are distinguishable from Stromer's Tameryraptor, writing "In contrast to SNSB-BSPG 1922 X 46 [Tameryraptor], all preserved maxillary teeth of Carcharodontosaurus saharicus show a more typical backwards curvature with the tip of the tooth positioned over the distal half of the tooth base", and the original Carcharodontosaurus syntypes do match the neotype in this regard. So maybe carcharodontosaurine teeth are diagnostic at lower levels. If someone wants to propose Carcharodontosaurus and Giganotosaurus can't be distinguished dentally, they should take a database of quantitative measurements and characters like Hendrickx's to demonstrate it. Finally, the fact the teeth are lost is part of what makes them less diagnostic because we only have short, outdated descriptions and two views of one tooth and one view of the other. There could have been differences in denticle shape, cross section, enamel texture, etc., but we'll never know unless they are later found.
Titanosaurus is in the same situation because Wilson and Upchurch (2003) just wrote "In summary, all six features forwarded by Lydekker in his diagnosis of T. indicus are now broadly distributed within Titanosauria. ... Because no diagnostic characters could be identified, T. indicus must be regarded as a nomen dubium." Again cases of "well, those characters are all shared with other taxa, time to sink it" and "well we didn't see any differences" [from what?], without even listing two other titanosaurs with supposedly similar enough caudals to be congeneric. People just don't put in the work. I still don't trust Titanosaurus is undiagnostic all these years later because titanosaur caudals are often used in diagnoses.
"Although the Texas material has been suggested to be distinct from Alamosaurus, the Utah material has never been suggested to be distinct (tmk anyway) aside from Greg Paul."
I had never looked at the situation before yesterday, but Gilmore's photo makes it pretty obvious Utetitan is also distinct from Alamosaurus in the scapula. It has the distally extended supraglenoid fossa like the Argentinian scapulae I was comparing, for example.
Mickey Mortimer
Maxwell Miles Candlen
Oct 13, 2025, 10:37:20 PM (5 days ago) Oct 13
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I’d like to echo the sentiment that many people enjoy the DMG because it’s an opportunity to have well-thought-out discussions over a period of time, as opposed to a hastily tapped-out Twitter thread or Discord chat. There are more appropriate venues for dialogues of such character, and I think many would agree that they would do best to stick to those places, rather than spilling over to the DMG.
There are a lot of interesting and important discussions to be had over the present publication, which luckily are happening beneath the noise, but constructing headcanon psychological profiles over why certain decisions were/were not made are neither productive nor desired by, I would assume, the majority of users. It takes all kinds of personalities and viewpoints to make a well-rounded community, so let’s engage with the actual arguments rather than bad-faith ad hominem attacks.
Maxwell Miles Candlen
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Stephen Poropat
Oct 13, 2025, 10:53:54 PM (5 days ago) Oct 13
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To paraphrase the unnamed protagonist in Fight Club, "On a long enough timeline, the survival rate for [any taxon named from a single element or suboptimal specimen for which a neotype is not designated] drops to zero."
I like the name Alamosaurus sanjuanensis. I'd like it to stay in use. But I agree with Greg that its holotype is not great and possibly non-diagnostic (I redescribed the "Alamosaurus" specimens in Uppsala in a 2013 paper published in GFF [not cited by Paul; but then it wasn't exactly earth-shattering: https://www.tandfonline.com/doi/abs/10.1080/11035897.2012.759268], and discussed its utility as a "form taxon").
Greg might be right about the North Horn specimen being distinct. If he is correct, maybe a new name is warranted. It is unfortunate that a ute (utility vehicle) in Australian English is a pick-up truck; I read Utetitan and my mind's eye sees a monster 4WD with a snorkel...
The North Horn specimen being designated the Alamosaurus neotype would be suboptimal, not least because it would render the name Alamosaurus sanjuanensis meaningless (as the North Horn specimen is not from the San Juan Basin, not from the Alamo Wash). At least the Carcharodontosaurus saharicus neotype derives from the Sahara, and prospective neotypes for Kronosaurus queenslandicus all derive from Queensland.
I think a neotype should eventually be chosen for Alamosaurus sanjuanensis - but it should ideally come from the Alamo Wash / San Juan Basin. If an appropriate specimen is not available (as the case seems to be), it can wait. The name can still be used, as it has been for ages, as a "form taxon" (the North Horn specimen has effectively been a proxy-type for it, but if we accept Utetitan, that cannot continue). Including Alamosaurus in phylogenetic analyses has always been problematic (but has been done; more often than not the North Horn specimen has provided the bulk of, if not all of, the data).
What would have made the present paper more useful, in my opinion, is:
a) a table of measurements so that the size disparity of the specimens in question could be established without having to leaf through a dozen other papers or to have to trust the article when it states that such and such a bone is bigger than another;
b) discussion of phylogenetically relevant characters observed in the material, and the implications thereof for placement of the various specimens within Titanosauria [a phylogenetic analysis including the best half dozen Maastrichtian sauropods from North America would be interesting to see]; and
c) pretty much any representation of the specimens that was not a simple outline drawing. 3D models would be best, of course, but in lieu of that new photos and/or shaded sketches.
In my opinion, Alamosauria would have been the best name for the clade (since it is unranked, acknowledges the antiquity of Alamosaurus relative to Utetitan, and reflects that fact that Alamosaurus is retained as valid in this paper). However, I can see that Greg has his reasons for dubbing it Utetitaninae and I agree that no matter what decision he'd made, he would have copped flack from someone. Perhaps the only thing that would have caused less debate would have been to choose a name that either did not derive from that of one of its constituents (as in Colossosauria) or did so only loosely (as in Lognkosauria).
It's hard not to reflect, as one stares into the flames of taxonomic teacup flare-ups like this, that washing our hands of binomens and dealing exclusively in specimen numbers would take so much emotion out of this process.
Greg: you may not intend your comments / papers to be as incendiary as they evidently are, but they do tend to wind people up (I'm definitely not immune, I'm often just so tired I can seldom make the effort to respond). That said: no-one on this list should be subjected to what Greg has been in the wake of this paper. I fully agree with Tim that ad hominem attacks having absolutely no place here; I am on the DMG mainly because of the phenomenal job that Ben Creisler does, not to see people getting abused.
Steve
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Dr Stephen F. Poropat
Deputy Director
Western Australian Organic and Isotope Geochemistry Centre
School of Earth and Planetary Sciences
Curtin University
Bentley, Western Australia
Australia 6102
Tim Williams
Oct 13, 2025, 11:17:40 PM (5 days ago) Oct 13
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Milo Gaillard <miloga...@gmail.com> wrote:
> One more thing. I talked to at least one sauropod researcher about this. He agrees that Alamosaurus should get a neotype.
> One more thing. I talked to at least one sauropod researcher about this. He agrees that Alamosaurus should get a neotype.
A neotype is no slum-dunk. A petition has to be submitted to the ICZN, and the Commission has to agree that a neotype for _Alamosaurus_ is necessary. Objections could be raised to the proposal - such as that the proposed neotype is not from the San Juan Basin; or that the original holotype might be diagnostic after all. See Mickey Mortimer's most recent DMG post as an example of the latter.
For Case 3700 (petition to replace _Diplodocus longus_ with _D. carnegii_ as the type species of _Diplodocus_, which I thought was a sensible idea), the Commission rejected the proposal (Opinion 2425).
For Case 3700 (petition to replace _Diplodocus longus_ with _D. carnegii_ as the type species of _Diplodocus_, which I thought was a sensible idea), the Commission rejected the proposal (Opinion 2425).
Stephen Poropat <stephen...@gmail.com> wrote:
> I like the name Alamosaurus sanjuanensis. I'd like it to stay in use. But I agree with Greg that its holotype is not great and possibly non-diagnostic (I redescribed the "Alamosaurus" specimens in Uppsala in a 2013 paper published in
> GFF [not cited by Paul; but then it wasn't exactly earth-shattering: https://www.tandfonline.com/doi/abs/10.1080/11035897.2012.759268], and discussed its utility as a "form taxon").
Steve is far too modest. The paper is also available here: www.researchgate.net/publication/257366962_Carl_Wiman's_sauropods_The_Uppsala_Museum_of_Evolution's_collection
Milo Gaillard
Oct 13, 2025, 11:24:31 PM (5 days ago) Oct 13
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Still, did you at least read my other reply about researchers choosing to ignore Alamosaurus supposedly being a nomen dubium before? Researchers can choose to ignore taxa being sunk.
Sinking Alamosaurus didn’t go work before. Why would it work again?
Then again, like Mickey said, it’s possible that Alamosaurus supposedly being undiagnostic isn’t convincing enough and that’s why subsequent researchers ignored it.
-Milo
Sent from my iPhone
On Oct 13, 2025, at 20:17, Tim Williams <tij...@gmail.com> wrote:
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Milo Gaillard
Oct 13, 2025, 11:26:31 PM (5 days ago) Oct 13
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Oh btw. All sauropod researchers ignored the ICZN’s rejection, tmk. Diplodocus longus is still considered to be a nomen dubium by them, and they still use the name Diplodocus, despite its type species still supposedly being undiagnostic.
Ethan Schoales
Oct 13, 2025, 11:27:32 PM (5 days ago) Oct 13
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Does everyone agree it’s undiagnostic?
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Milo Gaillard
Oct 13, 2025, 11:29:11 PM (5 days ago) Oct 13
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D. longus? Yes. The vast majority of sauropod researchers find D. longus to be undiagnostic.
Ethan Schoales
Oct 13, 2025, 11:30:06 PM (5 days ago) Oct 13
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I still hope we aren’t eventually forced to abandon the name Diplodocus and replace it with who knows what.
Sean McKelvey
Oct 13, 2025, 11:30:28 PM (5 days ago) Oct 13
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Stephen, I largely agree with all the points you made, and I am man enough to admit that I allowed emotion to get the better of me. I apologize for any ad hominem statements I may have made. That being said, it might be worth considering more thoroughly how a statement could be interpreted by others (I include myself in this, I am not innocent here).
Simply put, the paper does indeed raise questions and certainly more work is needed to clear up what the situation regarding Maastrichtian North American Titanosaurs exactly is. I'm just not exactly convinced by the argument in the paper at hand, and I think that's a perfectly reasonable position to hold until further data can back it up or dismiss it. The Dinosaur Heretic
Oct 13, 2025, 11:30:52 PM (5 days ago) Oct 13
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It’s the longus part, not the Diplodocus part.
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Milo Gaillard
Oct 13, 2025, 11:33:02 PM (5 days ago) Oct 13
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Not a chance
Sent from my iPhone
On Oct 13, 2025, at 20:30, Ethan Schoales <ethan.s...@gmail.com> wrote:
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John D'Angelo
Oct 14, 2025, 12:10:27 AM (5 days ago) Oct 14
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Nowhere in the ICZN is there a rule that a species being a nomen dubium prevents it from being the type species of a valid genus. Because the nominal species D. longus fell within the clade that Tschopp et al. want to call Diplodocus, the name Diplodocus is validly applied to that clade by article 61.1.1 of the ICZN, regardless of whether D. longus is a valid taxonomic species. So Tschopp et al.'s petition would not have had any effect on the validity of Diplodocus, which is one of the reasons it was rejected: they were trying to fix a problem that didn't exist.
Tschopp et al.'s reasoning in considering D. longus a nomen dubium is
that they were unable to identify autapomorphies in the holotype.
However, a species doesn't need autapomorphies to be valid, and in fact
species are usually better diagnosed by combinations of characters than
by autapomorphies. I think YPM 1920 is probably diagnostic at the
species level. See my SVP abstract from last year for more details ;-)
However, in my opinion, Tschopp et al. should have invoked article 75.6 of the ICZN and petitioned to designate AMNH 223 the neotype of D. longus, as it was widely recognized as an exemplar of D. longus for over a century. Doing so would have stabilized Diplodocus taxonomy just as well, while being better-founded in ICZN rules.
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Milo Gaillard
Oct 14, 2025, 12:14:43 AM (5 days ago) Oct 14
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Very good points made here. A good chunk of the examples of taxa getting sunk into nomina dubia could be ignored, simply because the arguments weren’t convincing enough. That being said, I still think they’d ignore cases that were probably more convincing.
Troodon was a nomen dubium from 2017-2025, and the reasons were pretty convincing imo. It was still getting used in the literature by some papers during that time. Furthermore, when the Troodon neotype proposal was published, despite being just a proposal, the vast majority still treated it as valid again. There’s even several papers this year that still use the name and treat it as valid, despite the neotype not being official. They already wanted to keep using the Troodon name in the first place.
It’s not like I’m even mad at them. In fact, I’m happy to use Troodon as valid again. My point is that the scientists can choose to ignore decisions being made about taxa. They don’t seem to care so much about these ICZN rules.
And if the scientists don’t care, then why should I?
But that’s just me. At the end of the day, names are just names. Not void of importance of course, but nothing to get riled up about. I just don’t see how abandoning Alamosaurus would be viable in the future, even if the holotype is undiagnostic (which you made clear that you don’t agree with btw).
-Milo
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On Oct 13, 2025, at 18:53, Mickey Mortimer <therizino...@gmail.com> wrote:
Milo Gallaird wrote- " I’ve spoken to several sauropod researchers myself. They all think that the type is undiagnostic below family level."
"Yet them calling it an undiagnostic taxon was ignored in subsequent papers."
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Milo Gaillard
Oct 14, 2025, 12:26:29 AM (5 days ago) Oct 14
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Very good points, John.
Thanks for clarification about the ICZN rules. It makes sense. If a genus has multiple species, but only the type is undiagnostic, then so what? That genus still has several very complete species to fall back on.
I guess my overall point is that I just fail to see what purpose abandoning the Alamosaurus name would serve or how it would even be viable in the future. This is already the case with several other taxa. See my previous emails for examples as to why.
If Alamosaurus was undiagnostic, I bet you that subsequent papers would just choose to ignore it. As I demonstrated in other emails in this thread, Lucas and Sullivan (2000) called Alamosaurus a nomen dubium and that was practically ignored by numerous subsequent papers (even before D’Emic et al (2011) found it to be diagnostic). I mean, Mike Taylor put Alamosaurus (which was supposedly an invalid, undiagnostic taxon at this time) in a phylogenetic analysis in his 2009 Giraffatitan paper. Need I say more.
So yeah. Something akin to an Alamosaurus neotype is just the only viable option I can see in the future, if the holotype proves to be undiagnostic. Sinking the name didn’t work before. Why would it work again?
-Milo
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On Oct 13, 2025, at 21:10, John D'Angelo <dangel...@gmail.com> wrote:
Mike Taylor
Oct 14, 2025, 2:53:56 AM (5 days ago) Oct 14
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Just to note that, contra Milo Gaillsrd, the undiagnosability of D. longus is far from unanimously agreed by sauropod workers. See the ICZN's rejection of the petition to nominate D. carnegii as the type species:
https://www.miketaylor.org.uk/tmp/PDF/ICZN2018_opinion%202425%20Diplodocus%20longus%20maintained.pdf
and the three comments in opposition to the petition that are cited therein.
(I think this was a bad decision by the ICZN, since the reality is that everyone treats CM 84 as defining what Diplodocus is anyway, but that ship has sailed.)
-- Mike.
Mickey Mortimer
Oct 14, 2025, 4:50:59 AM (5 days ago) Oct 14
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"I think this was a bad decision by the ICZN, since the reality is that everyone treats CM 84 as defining what Diplodocus is anyway, but that ship has sailed."
I liked it, and got a chance to officially influence matters as one of those three comments in opposition. Note the similarities to the Alamosaurus Lucas and Sullivan case-"While the authors view D. longus as indeterminate, this opinion is based on a
phylogenetic analysis published as Tschopp et al. (2015), which merely found it had no
unique characters within those used to construct the data matrix. This led to it forming a
polytomy with the D. carnegii holotype, the D. carnegii paratype, and a clade of specimens
forming D. hallorum. Yet the particular characters used to construct a matrix do
not represent every potential aspect of morphological variability, and indeed depending
on the matrix used many diagnostic species would score identically in many analyses.
Nor is the undiagnostic status of D. longus even consensus, as the previous publication
to examine the problem (McIntosh & Carpenter, 1998) concluded D. longus was distinct
based on having shorter caudals with pleurocoels that extend less far distally in the tail,
and being stratigraphically older as well. Tschopp & Mateus (2016) did not engage with
these arguments..."
"The case of
Stegosaurus is similar in that the original type was never agreed by consensus to be
undiagnostic, had a previous author argue for diagnosability, and was agreed to belong to
the genus in question. In that case too, its author argued 'Stegosaurus armatus MARSH
1877 is a nomen dubium, ...' The result of that decision, when the original holotype has
never even been described in detail or in a modern context, should be avoided in the
future."
You don't just get to say "well we didn't see any differences", although the Diplodocus and Stegosaurus cases were worse because other authors had recently defended the validity of both D. longus and S.armatus, whereas I'm unsure if anyone tried to diagnose Alamosaurus by its scapular characters prior to 2000. I don't follow the ornithischian lit as closely, but the Stegosaurus situation seems to be much like Carcharodontosaurus and Titanosaurus, where based on one person's diagnosis, the S. armatus type didn't preserve those characters, without actually going in and looking into the differences between Stegosaurus and Hesperosaurus and seeing which one the holotype was most like - "Galton (2010) noted that the holotype of Stegosaurus armatus displayed none of the five putative autapomorphic characters listed by Maidment et al. (2008) for the species armatus in its current usage. ... Consequently, Galton (2010) indicated the
need to petition the Commission to designate Stegosaurus stenops Marsh, 1887 as the new type species of Stegosaurus Marsh, 1877 to replace S. armatus Marsh, 1877." (Galton's 2011 ICZN petition).To satisfy my own curiosity, I've begun a new series on my blog testing the validity of Titanosaurus. It's an example of what kind of analysis SHOULD happen before you declare a taxon indeterminate, let alone petition the ICZN. The first part is out today-
The Theropod Database Blog: The Titanosaurus (in?)validity project Part 1 - Saltasaurus .
Mickey Mortimer
Mike Taylor
Oct 14, 2025, 5:03:05 AM (5 days ago) Oct 14
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I'm not going to re-litigate the failed Diplodocus petition. I just left a note about my own opinion to give context. You will recall my point was precisely that not everyone agrees D. longus is non-diagnostic.
-- Mike.
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Milo Gaillard
Oct 14, 2025, 7:07:44 AM (5 days ago) Oct 14
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Yeah, I get the sentiment, Mike. Something tells me that this my suggestions and takes here are probably a rehash of the failed Diplodocus petition. I know that’s some people find D. longus to be diagnostic (including John here), but most researchers who I talked to seemed to think that it’s not.
Btw, if you want my opinion, if it came down to giving Alamosaurus sanjuanensis a neotype, I think that TMM 41541-1 would probably be the best candidate because:
1) Utetitan/A. zellaguymondeweyae apparently has differences in the scapula, even going by photos. So, I guess it can stay?
2) Most of USNM 15560 is a tail. The thing is that apparently the caudals between different sauropod taxa in the same family can be impossible to tell apart from each other, such as those between Diplodocus and Barosaurus (at least according to Brian Curtice, who I spoke to about this), so it’s possible the same is true for late Cretaceous North American sauropods.
3) I know what Utetitan zellaguymondeweyae was named after, so I kind of feel bad for spitting on the face of Greg Paul’s grandmother. I know that’s not exactly a scientific reason, but still.
That’s just me though. I’m unsure if my suggestions will go anywhere. Maybe me and certain other researchers are wrong and the A. sanjuanensis material is diagnostic. We’ll just see what other researchers do.
Thank you for reading,
-Milo Gaillard
Milo Gaillard
Oct 14, 2025, 7:12:36 AM (5 days ago) Oct 14
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Oh wow. Did I actually inspire you to write a series of blog posts evaluating the validity and diagnostic potential of Titanosaurus indicus?
Anyway, that was a pretty interesting read. Glad this whole thread inspired discussion.
-Milo
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On Oct 14, 2025, at 01:51, Mickey Mortimer <therizino...@gmail.com> wrote:
"I think this was a bad decision by the ICZN, since the reality is that everyone treats CM 84 as defining what Diplodocus is anyway, but that ship has sailed."
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Gregory Paul
Oct 14, 2025, 1:00:23 PM (5 days ago) Oct 14
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All dinosaur cases I can think of submitted to the ICZN - Iguanodon, Allosaurus, Diplodocus, Archaeopteryx, Stegosaurus, Coelophysis -- had two characteristics. The taxa were well known by the general public and warranted saving. And the available neotype was a well preserved specimen.
None of this applies to Alamosaurus, which as much as it is liked by those of us who know about it, while most in the public don't know Alamosaurus from that horrible tragic battle that killed all those poor Texans (oops, there I go again citing a tragedy -- but that affair was really about antebellum Americans keeping their slaves in emancipated Mexico so to hell with them, including Crockett). And there is no good neotype for Alamosaurus.
This proposal would be to take a so-so skull-less specimen made of mainly the trunk, pelvis and some limb elements, but no needed scapula, describing it in detail which is a good idea but I don't know if that will happen in the not distant future, and then going to the ICZN and asking them to make it the neotype of A. s., apparently displacing U. z. which is based on a decent specimen that includes the diagnostic scapula. That while leaving the specimens that do belong to the same taxon as the A. s. holotype taxonomic floaters, until a new name can be applied to those?
This is so not happening. No one will do it, if they tried the ICZN editors would likely reject posting it, and if that happened the petition would very likely fail. After all the Diplodocus effort failed even though CM 84 should be the neotype.
If there is to be a neotype A. s., it needs to be a very nice specimen with shoulder blade from reasonably nearby in space and time to the holotype. Which might be found this century or next.
GSPaul
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