Eusuchian cranial fossils from Upper Cretaceous of Pyrenees + turtle humeri + Smilodon saber eruption + Megantereon + merganser evolution + more
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Ben Creisler
May 8, 2024, 2:57:11 PM5/8/24
to dinos...@usc.edu, DinosaurMa...@googlegroups.com
Ben Creisler
Some recent non-dino papers:
Riccardo Rocchi & Bernat Vila (2024)
New eusuchian cranial remains from the Upper Cretaceous of the southern Pyrenees
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2024.2350551
https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2350551
Allodaposuchids were among the most common crocodyliforms in the Upper Cretaceous of Europe. The clade, recently erected to include a large number of species described in the last decade, seems to hold a remarkable diversity that has generated systematic controversies. Here we describe an interorbital fragment of an eusuchian crocodyliform, collected in the late 1950s in the locality of Suterranya-Mina de lignit (Lleida, Spain), from the lower Maastrichtian deposits of the Tremp Group, in the southern Pyrenees. The specimen is here identified as an allodaposuchid; some already described teeth, probably found together with the cranial remains and therefore here assigned to the same individual, reinforce this interpretation. The interorbital region of the specimen shows some important similarities with Allodaposuchus subjuniperus, reported only from the upper Maastrichtian levels of the Tremp Group, while it clearly differs from Allodaposuchus palustris, which is already reported in the lower Maastrichtian transitional deposits close to Suterranya-Mina de lignit locality. This study shows that at least three different species of allodaposuchids can be found in the lower Maastrichtian deposits of the Tremp Group.
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New eusuchian cranial remains from the Upper Cretaceous of the southern Pyrenees
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2024.2350551
https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2350551
Allodaposuchids were among the most common crocodyliforms in the Upper Cretaceous of Europe. The clade, recently erected to include a large number of species described in the last decade, seems to hold a remarkable diversity that has generated systematic controversies. Here we describe an interorbital fragment of an eusuchian crocodyliform, collected in the late 1950s in the locality of Suterranya-Mina de lignit (Lleida, Spain), from the lower Maastrichtian deposits of the Tremp Group, in the southern Pyrenees. The specimen is here identified as an allodaposuchid; some already described teeth, probably found together with the cranial remains and therefore here assigned to the same individual, reinforce this interpretation. The interorbital region of the specimen shows some important similarities with Allodaposuchus subjuniperus, reported only from the upper Maastrichtian levels of the Tremp Group, while it clearly differs from Allodaposuchus palustris, which is already reported in the lower Maastrichtian transitional deposits close to Suterranya-Mina de lignit locality. This study shows that at least three different species of allodaposuchids can be found in the lower Maastrichtian deposits of the Tremp Group.
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Václav Gvoždík, Matej Dolinay, Ange-Ghislain Zassi-Boulou, Alan R. Lemmon, Emily M. Lemmon and Miroslav Procházka (2024)
Central African dwarf crocodiles found in syntopy are comparably divergent to South American dwarf caimans
Biology Letters 20(5): 20230448
doi: https://doi.org/10.1098/rsbl.2023.0448
https://royalsocietypublishing.org/doi/10.1098/rsbl.2023.0448
Recent molecular taxonomic advancements have expanded our understanding of crocodylian diversity, revealing the existence of previously overlooked species, including the Congo dwarf crocodile (Osteolaemus osborni) in the central Congo Basin rainforests. This study explores the genomic divergence between O. osborni and its better-known relative, the true dwarf crocodile (Osteolaemus tetraspis), shedding light on their evolutionary history. Field research conducted in the northwestern Republic of the Congo uncovered a locality where both species coexist in sympatry/syntopy. Genomic analysis of sympatric individuals reveals a level of divergence comparable to that between ecologically similar South American dwarf caimans (Paleosuchus palpebrosus and Paleosuchus trigonatus), suggesting parallel speciation in the Afrotropics and Neotropics during the Middle to Late Miocene, 10–12 Ma. Comparison of the sympatric and allopatric dwarf crocodiles indicates no gene flow between the analysed sympatric individuals of O. osborni and O. tetraspis. However, a larger sample will be required to answer the question of whether or to what extent these species hybridize. This study emphasizes the need for further research on the biology and conservation status of the Congo dwarf crocodile, highlighting its significance in the unique biodiversity of the Congolian rainforests and thus its potential as a flagship species.
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Free pdf:
Guilherme Hermanson, Fernando A. M. Arnal, Tomasz Szczygielski & Serjoscha W. Evers (2024)
A systematic comparative description of extant turtle humeri, with comments on humerus disparity and evolution based on fossil comparisons
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.25450
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25450
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25450
The humerus is central for locomotion in turtles as quadrupedal animals. Osteological variation across testudine clades remains poorly documented. Here, we systematically describe the humerus anatomy for all major extant turtle clades based on 38 species representing the phylogenetic and ecological diversity of crown turtles. Three Late Triassic species of shelled stem turtles (Testudindata) are included to establish the plesiomorphic humerus morphology. Our work is based on 3D models, establishing a publicly available digital database. Previously defined terms for anatomical sides of the humerus (e.g., dorsal, ventral) are often not aligned with the respective body sides in turtles and other quadrupedal animals with sprawling gait. We propose alternative anatomical directional terms to simplify communication: radial and ulnar (the sides articulating with the radius/ulna), capitular (the side bearing the humeral head), and intertubercular (opposite to capitular surface). Turtle humeri show low morphological variation with exceptions concentrated in locomotory specialists. We propose 15 discrete characters to summarize osteological variation for future phylogenetic studies. Disparity analyses comparing non-shelled and shelled turtles indicate that the presence of the shell constrains humerus variation. Flippered aquatic turtles are released from this constraint and significantly increase overall disparity. Ontogenetic changes of turtle humeri are related to increased ossification and pronunciation of the proximal processes, the distal articulation areas, and the closure of the ectepicondylar groove to a foramen. Some turtle species retain juvenile features into adulthood and provide evidence for paedomorphic evolution. We review major changes of turtle humerus morphology throughout the evolution of its stem group.
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Free pdf:
Z. Jack Tseng (2024)
Bending performance changes during prolonged canine eruption in saber-toothed carnivores: A case study of Smilodon fatalis
The Anatomical Record (advance line publication)
doi: https://doi.org/10.1002/ar.25447
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25447
Bending performance changes during prolonged canine eruption in saber-toothed carnivores: A case study of Smilodon fatalis
The Anatomical Record (advance line publication)
doi: https://doi.org/10.1002/ar.25447
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25447
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25447
The canine of saber-toothed predators represents one of the most specialized dental structures known. Hypotheses about the function of hypertrophied canines range from display and conspecific interaction, soft food processing, to active prey acquisition. Recent research on the ontogenetic timing of skull traits indicates the adult canine can take years to fully erupt, but the consequences of prolonged eruption on inferences of canine functional morphology are missing from current discourse and have not been quantified. Here I evaluate hypotheses about adult canine bending strength and stiffness, respectively, during eruption in the felid Smilodon fatalis. Simulated eruption sequences of three adult canines were generated from specimen models to assess shifting cross-sectional geometry properties, and bending strength and stiffness under laterally directed loads were estimated using finite element analysis. Consistent with beam theory expectations, S. fatalis canine cross-sectional geometry is optimized for increased bending strength with increased erupted height. However, canine cross-sectional geometry changes through eruption exaggerate rather than minimize lateral deflection. Spatial constraint for maximum root length from adjacent sensory structures in the maxilla and the recently identified universal power law are hypothesized to limit the growth capacity of canine anteroposterior length and, consequently, maintenance of bending stiffness through eruption. Instead, the joint presence of the deciduous and adult canines for >50% of the adult canine eruption period effectively increases canine mediolateral width and brings bending strength and stiffness estimates closer to theoretical optima. Similarly prolonged retention of deciduous canines in other sabertooths suggests dual-canine buttressing is a convergently evolved strategy to maximize bending strength and stiffness.
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News:
Saber-Toothed Tigers Held onto Their Milk Teeth to Stabilize Their Sabers, Study Suggests
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Free pdf:
Christopher M. Stimpson (2024)
Siwalik sabrecats: review and revised diagnosis of Megantereon fossils from the foothills of the Himalaya
Royal Society Open Science 11(5): 231788
doi: https://doi.org/10.1098/rsos.231788
https://royalsocietypublishing.org/doi/10.1098/rsos.231788
Free pdf:
https://royalsocietypublishing.org/doi/epdf/10.1098/rsos.231788
The diagnosis of different fossil taxa in small collections from disparate geographical and temporal contexts is a common challenge in palaeontology. The likely number of morphospecies of the extinct sabretooth cat Megantereon is a classic example and subject of long-standing debate. While analyses of global fossil collections have provided insights and hypotheses, specimens from the foothills of the Himalaya—the Siwaliks—have been overlooked in recent treatments due to poor characterization and a confused taxonomic history. Here, this oversight is addressed. Craniodental fossils from the Siwaliks are revisited and their taxonomic status is reviewed. Morphological and metric characteristics are described, and qualitative and quantitative comparisons with congenerics are performed with published descriptions and datasets. The Lower Pleistocene Siwalik Megantereon are among the largest known forms in the genus. Advanced characteristics include reduced upper third premolars and long but comparatively narrow carnassial teeth. While dietary specialism can constrain morphological diversity, statistical analyses, including controls for body size effects, detected significant metric differences in the mandibles in comparison with congenerics. Within current paradigms, the status of Megantereon falconeri as a distinct morphospecies is upheld. A revised diagnosis is provided and the taxonomic affinities of M. falconeri are considered.
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Gymnosperm leaves (Cretaceous, Argentina) are studied by infrared spectroscopy.
A novel mathematical model is proposed to estimate the density of leaves' tissues.
Fracture resistance, stiffness, and metabolic cost of construction are determined.
The possible leaves' nutritional quality for herbivores consumption is addressed.
Abstract
This study provides the first data on the relationship between chemical composition and biomechanical/physiological characteristics of foliar gymnosperm compressions from the Lower Cretaceous of Santa Cruz, Argentina. Studied taxa include: Squamastrobus tigrensis, Pseudoctenis ornata, Ginkgoites tigrensis, Ruflorinia orlandoi, and Ptilophyllum micropapillosum. The properties determined include: density, tensile strength (resistance to fracture), tensile modulus of elasticity (stiffness), and leaf mass per area (metabolic cost of tissue construction). They are calculated using a 3D-multivariate model based on data obtained by Fourier transform infrared (FTIR) spectroscopy and trait relationships linking density and the properties mentioned above. Samples have a predominantly aromatic chemical composition with variable carbonyl contents. The chemical groups detected are associated with diagenetically-resistant molecules, possibly including lignins, phenylpropanoids, tannins, and resin-like compounds. The results indicate that these plant taxa may have allocated variable amounts of resources (metabolic costs) for the development of aromatic, biomechanically resistant, and relatively long-lived foliar tissues. The determined chemical, biomechanical, and physiological properties of these leaves suggest their potential as a food source for herbivores. Thus, S. tigrensis leaves might have been unpleasantly astringent, difficult to eat and digest due to their hard tissues, and possibly even hazardous. Conversely, the leaves of G. tigrensis, P. ornata, R. orlandoi, and P. micropapillosum may have been easy to eat due to their softer tissues, offering food of intermediate-high nutritional value. The use of FTIR spectroscopy proves useful to perform detailed and realistic studies on the biomechanics, physiology, and autecology of extinct plants.
Elisa Barreto, Mannfred M. A. Boehm, Ezgi Ogutcen, Stefan Abrahamczyk, Michael Kessler, Jordi Bascompte, Agnes S. Dellinger, Carolina Bello, D. Matthias Dehling, François Duchenne, Miriam Kaehler, Laura P. Lagomarsino, Lúcia G. Lohmann, María A. Maglianesi, Hélène Morlon, Nathan Muchhala, Juan Francisco Ornelas, Mathieu Perret, Nelson R. Salinas, Stacey D. Smith, Jana C. Vamosi, Isabela G. Varassin & Catherine H. Graham (2024)
Macroevolution of the plant–hummingbird pollination system
Biological Reviews (advance online publication)
doi: https://doi.org/10.1111/brv.13094
https://onlinelibrary.wiley.com/doi/10.1111/brv.13094
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1111/brv.13094
Plant–hummingbird interactions are considered a classic example of coevolution, a process in which mutually dependent species influence each other's evolution. Plants depend on hummingbirds for pollination, whereas hummingbirds rely on nectar for food. As a step towards understanding coevolution, this review focuses on the macroevolutionary consequences of plant–hummingbird interactions, a relatively underexplored area in the current literature. We synthesize prior studies, illustrating the origins and dynamics of hummingbird pollination across different angiosperm clades previously pollinated by insects (mostly bees), bats, and passerine birds. In some cases, the crown age of hummingbirds pre-dates the plants they pollinate. In other cases, plant groups transitioned to hummingbird pollination early in the establishment of this bird group in the Americas, with the build-up of both diversities coinciding temporally, and hence suggesting co-diversification. Determining what triggers shifts to and away from hummingbird pollination remains a major open challenge. The impact of hummingbirds on plant diversification is complex, with many tropical plant lineages experiencing increased diversification after acquiring flowers that attract hummingbirds, and others experiencing no change or even a decrease in diversification rates. This mixed evidence suggests that other extrinsic or intrinsic factors, such as local climate and isolation, are important covariables driving the diversification of plants adapted to hummingbird pollination. To guide future studies, we discuss the mechanisms and contexts under which hummingbirds, as a clade and as individual species (e.g. traits, foraging behaviour, degree of specialization), could influence plant evolution. We conclude by commenting on how macroevolutionary signals of the mutualism could relate to coevolution, highlighting the unbalanced focus on the plant side of the interaction, and advocating for the use of species-level interaction data in macroevolutionary studies.
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John E. Gallucci, Grace Woolslayer, Kelsey Barker, Brian Kibelstis, Allison R. Tumarkin-Deratzian, Paul V. Ullmann, David E. Grandstaff and Dennis O. Terry (2024)
Controls on Soft Tissue and Cellular Preservation in Late Eocene and Oligocene Vertebrate Fossils from the White River and Arikaree Groups of Nebraska, South Dakota, and Wyoming
Minerals 14(5): 497
doi: https://doi.org/10.3390/min14050497
https://www.mdpi.com/2075-163X/14/5/497
Previous studies on microtaphonomy have identified multiple types of organic microstructures in fossil vertebrates from a variety of time periods and past environmental settings. This study investigates potential taphonomic, paleoenvironmental, and paleoclimatic controls on soft tissue and cellular preservation in fossil bone. To this end, fifteen vertebrate fossils were studied: eight fossils collected from the Oligocene Sharps Formation of the Arikaree Group in Badlands National Park, South Dakota, and seven fossils from formations in the underlying White River Group, including the Oligocene Brule Formation of Badlands National Park, and the Eocene Chadron Formation of Flagstaff Rim, Wyoming; Toadstool Geologic Park, Nebraska; and Badlands National Park, South Dakota. A portion of each fossil was demineralized to identify any organic microstructures preserved within the fossils. We investigated several factors which may have influenced cellular/soft tissue decay and/or preservation pathways, including taxonomic identity, paleoclimatic conditions, depositional environment, and general diagenetic history (as interpreted through thin section analysis). Soft tissue microstructures were preserved in all fossil samples, and cellular structures morphologically consistent with osteocytes were recovered from 11 of the 15 fossil specimens. Preservation of these microstructures was found to be independent of taxonomy, paleoclimate regime, apatite crystallinity, depositional environment, and general diagenetic history, indicating that biogeochemical reactions operating within microenvironments within skeletal tissues, such as within individual osteocyte lacunae or Haversian canals, may exert stronger controls on soft tissue and biomolecular decay or stabilization than external environmental (or climatic) conditions.
Free pdf:
Nicolas J Rawlence, Alexander J F Verry, Theresa L Cole, Lara D Shepherd, Alan J D Tennyson, Murray Williams, Jamie R Wood & Kieren J Mitchell (2024)
Ancient mitogenomes reveal evidence for the Late Miocene dispersal of mergansers to the Southern Hemisphere
Zoological Journal of the Linnean Society, zlae040
doi: https://doi.org/10.1093/zoolinnean/zlae040
https://academic.oup.com/zoolinnean/advance-article/doi/10.1093/zoolinnean/zlae040/7666678
Mergansers are riverine and coastal piscivorous ducks that are widespread throughout North America and Eurasia but uncommon in the Southern Hemisphere. One species occurs in South America and at least two extinct species are known from New Zealand. It has been proposed that these Southern Hemisphere merganser lineages were founded by at least two independent dispersal events from the Northern Hemisphere. However, some morphological and behavioural evidence suggests that Southern Hemisphere mergansers may form a monophyletic clade that descended from only a single dispersal event from the Northern Hemisphere. For example, Southern Hemisphere mergansers share several characteristics that differ from Northern Hemisphere mergansers (e.g. non-migratory vs. migratory, sexual monochromatism vs. sexual dichromatism, long vs. short pair bonds). We sequenced complete mitogenomes from the Brazilian merganser and an extinct merganser from New Zealand—the Auckland Island merganser. Our results show that the Brazilian and Auckland Island mergansers are not sister-taxa, and probably descend from two separate colonization events from the Northern Hemisphere at least 7 Mya. Nuclear (palaeo)genomic data may help to further resolve the relationship between living and extinct mergansers, including merganser fossils from New Zealand that have not been subjected to palaeogenetic analysis.
Nicolas J Rawlence, Alexander J F Verry, Theresa L Cole, Lara D Shepherd, Alan J D Tennyson, Murray Williams, Jamie R Wood & Kieren J Mitchell (2024)
Ancient mitogenomes reveal evidence for the Late Miocene dispersal of mergansers to the Southern Hemisphere
Zoological Journal of the Linnean Society, zlae040
doi: https://doi.org/10.1093/zoolinnean/zlae040
https://academic.oup.com/zoolinnean/advance-article/doi/10.1093/zoolinnean/zlae040/7666678
Mergansers are riverine and coastal piscivorous ducks that are widespread throughout North America and Eurasia but uncommon in the Southern Hemisphere. One species occurs in South America and at least two extinct species are known from New Zealand. It has been proposed that these Southern Hemisphere merganser lineages were founded by at least two independent dispersal events from the Northern Hemisphere. However, some morphological and behavioural evidence suggests that Southern Hemisphere mergansers may form a monophyletic clade that descended from only a single dispersal event from the Northern Hemisphere. For example, Southern Hemisphere mergansers share several characteristics that differ from Northern Hemisphere mergansers (e.g. non-migratory vs. migratory, sexual monochromatism vs. sexual dichromatism, long vs. short pair bonds). We sequenced complete mitogenomes from the Brazilian merganser and an extinct merganser from New Zealand—the Auckland Island merganser. Our results show that the Brazilian and Auckland Island mergansers are not sister-taxa, and probably descend from two separate colonization events from the Northern Hemisphere at least 7 Mya. Nuclear (palaeo)genomic data may help to further resolve the relationship between living and extinct mergansers, including merganser fossils from New Zealand that have not been subjected to palaeogenetic analysis.
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José A. D'Angelo, Maiten A. Lafuente Diaz & Georgina M. Del Fueyo (2024)
Sweet or bitter? Preliminary data on the biomechanics, physiology, and possible nutritional quality of Cretaceous gymnosperms leaves (Patagonia, Argentina)
Review of Palaeobotany and Palynology 105129
doi: https://doi.org/10.1016/j.revpalbo.2024.105129
https://www.sciencedirect.com/science/article/abs/pii/S0034666724000800
Highlights
Sweet or bitter? Preliminary data on the biomechanics, physiology, and possible nutritional quality of Cretaceous gymnosperms leaves (Patagonia, Argentina)
Review of Palaeobotany and Palynology 105129
doi: https://doi.org/10.1016/j.revpalbo.2024.105129
https://www.sciencedirect.com/science/article/abs/pii/S0034666724000800
Highlights
Gymnosperm leaves (Cretaceous, Argentina) are studied by infrared spectroscopy.
A novel mathematical model is proposed to estimate the density of leaves' tissues.
Fracture resistance, stiffness, and metabolic cost of construction are determined.
The possible leaves' nutritional quality for herbivores consumption is addressed.
Abstract
This study provides the first data on the relationship between chemical composition and biomechanical/physiological characteristics of foliar gymnosperm compressions from the Lower Cretaceous of Santa Cruz, Argentina. Studied taxa include: Squamastrobus tigrensis, Pseudoctenis ornata, Ginkgoites tigrensis, Ruflorinia orlandoi, and Ptilophyllum micropapillosum. The properties determined include: density, tensile strength (resistance to fracture), tensile modulus of elasticity (stiffness), and leaf mass per area (metabolic cost of tissue construction). They are calculated using a 3D-multivariate model based on data obtained by Fourier transform infrared (FTIR) spectroscopy and trait relationships linking density and the properties mentioned above. Samples have a predominantly aromatic chemical composition with variable carbonyl contents. The chemical groups detected are associated with diagenetically-resistant molecules, possibly including lignins, phenylpropanoids, tannins, and resin-like compounds. The results indicate that these plant taxa may have allocated variable amounts of resources (metabolic costs) for the development of aromatic, biomechanically resistant, and relatively long-lived foliar tissues. The determined chemical, biomechanical, and physiological properties of these leaves suggest their potential as a food source for herbivores. Thus, S. tigrensis leaves might have been unpleasantly astringent, difficult to eat and digest due to their hard tissues, and possibly even hazardous. Conversely, the leaves of G. tigrensis, P. ornata, R. orlandoi, and P. micropapillosum may have been easy to eat due to their softer tissues, offering food of intermediate-high nutritional value. The use of FTIR spectroscopy proves useful to perform detailed and realistic studies on the biomechanics, physiology, and autecology of extinct plants.
===
Free pdf:
Elisa Barreto, Mannfred M. A. Boehm, Ezgi Ogutcen, Stefan Abrahamczyk, Michael Kessler, Jordi Bascompte, Agnes S. Dellinger, Carolina Bello, D. Matthias Dehling, François Duchenne, Miriam Kaehler, Laura P. Lagomarsino, Lúcia G. Lohmann, María A. Maglianesi, Hélène Morlon, Nathan Muchhala, Juan Francisco Ornelas, Mathieu Perret, Nelson R. Salinas, Stacey D. Smith, Jana C. Vamosi, Isabela G. Varassin & Catherine H. Graham (2024)
Macroevolution of the plant–hummingbird pollination system
Biological Reviews (advance online publication)
doi: https://doi.org/10.1111/brv.13094
https://onlinelibrary.wiley.com/doi/10.1111/brv.13094
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1111/brv.13094
Plant–hummingbird interactions are considered a classic example of coevolution, a process in which mutually dependent species influence each other's evolution. Plants depend on hummingbirds for pollination, whereas hummingbirds rely on nectar for food. As a step towards understanding coevolution, this review focuses on the macroevolutionary consequences of plant–hummingbird interactions, a relatively underexplored area in the current literature. We synthesize prior studies, illustrating the origins and dynamics of hummingbird pollination across different angiosperm clades previously pollinated by insects (mostly bees), bats, and passerine birds. In some cases, the crown age of hummingbirds pre-dates the plants they pollinate. In other cases, plant groups transitioned to hummingbird pollination early in the establishment of this bird group in the Americas, with the build-up of both diversities coinciding temporally, and hence suggesting co-diversification. Determining what triggers shifts to and away from hummingbird pollination remains a major open challenge. The impact of hummingbirds on plant diversification is complex, with many tropical plant lineages experiencing increased diversification after acquiring flowers that attract hummingbirds, and others experiencing no change or even a decrease in diversification rates. This mixed evidence suggests that other extrinsic or intrinsic factors, such as local climate and isolation, are important covariables driving the diversification of plants adapted to hummingbird pollination. To guide future studies, we discuss the mechanisms and contexts under which hummingbirds, as a clade and as individual species (e.g. traits, foraging behaviour, degree of specialization), could influence plant evolution. We conclude by commenting on how macroevolutionary signals of the mutualism could relate to coevolution, highlighting the unbalanced focus on the plant side of the interaction, and advocating for the use of species-level interaction data in macroevolutionary studies.
====
Free pdf:
John E. Gallucci, Grace Woolslayer, Kelsey Barker, Brian Kibelstis, Allison R. Tumarkin-Deratzian, Paul V. Ullmann, David E. Grandstaff and Dennis O. Terry (2024)
Controls on Soft Tissue and Cellular Preservation in Late Eocene and Oligocene Vertebrate Fossils from the White River and Arikaree Groups of Nebraska, South Dakota, and Wyoming
Minerals 14(5): 497
doi: https://doi.org/10.3390/min14050497
https://www.mdpi.com/2075-163X/14/5/497
Previous studies on microtaphonomy have identified multiple types of organic microstructures in fossil vertebrates from a variety of time periods and past environmental settings. This study investigates potential taphonomic, paleoenvironmental, and paleoclimatic controls on soft tissue and cellular preservation in fossil bone. To this end, fifteen vertebrate fossils were studied: eight fossils collected from the Oligocene Sharps Formation of the Arikaree Group in Badlands National Park, South Dakota, and seven fossils from formations in the underlying White River Group, including the Oligocene Brule Formation of Badlands National Park, and the Eocene Chadron Formation of Flagstaff Rim, Wyoming; Toadstool Geologic Park, Nebraska; and Badlands National Park, South Dakota. A portion of each fossil was demineralized to identify any organic microstructures preserved within the fossils. We investigated several factors which may have influenced cellular/soft tissue decay and/or preservation pathways, including taxonomic identity, paleoclimatic conditions, depositional environment, and general diagenetic history (as interpreted through thin section analysis). Soft tissue microstructures were preserved in all fossil samples, and cellular structures morphologically consistent with osteocytes were recovered from 11 of the 15 fossil specimens. Preservation of these microstructures was found to be independent of taxonomy, paleoclimate regime, apatite crystallinity, depositional environment, and general diagenetic history, indicating that biogeochemical reactions operating within microenvironments within skeletal tissues, such as within individual osteocyte lacunae or Haversian canals, may exert stronger controls on soft tissue and biomolecular decay or stabilization than external environmental (or climatic) conditions.
===
Mickey Mortimer
May 10, 2024, 8:14:57 AM5/10/24
to Dinosaur Mailing Group
"Guilherme Hermanson, Fernando A. M. Arnal, Tomasz Szczygielski & Serjoscha W. Evers (2024)
A
systematic comparative description of extant turtle humeri, with
comments on humerus disparity and evolution based on fossil comparisons
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.25450
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25450
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25450
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.25450
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25450
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25450
The humerus is central for locomotion in turtles as quadrupedal animals. Osteological variation across testudine clades remains poorly documented. Here, we systematically describe the humerus anatomy for all major extant turtle clades based on 38 species representing the phylogenetic and ecological diversity of crown turtles. Three Late Triassic species of shelled stem turtles (Testudindata) are included to establish the plesiomorphic humerus morphology. Our work is based on 3D models, establishing a publicly available digital database. Previously defined terms for anatomical sides of the humerus (e.g., dorsal, ventral) are often not aligned with the respective body sides in turtles and other quadrupedal animals with sprawling gait. We propose alternative anatomical directional terms to simplify communication: radial and ulnar (the sides articulating with the radius/ulna), capitular (the side bearing the humeral head), and intertubercular (opposite to capitular surface). Turtle humeri show low morphological variation with exceptions concentrated in locomotory specialists. We propose 15 discrete characters to summarize osteological variation for future phylogenetic studies. Disparity analyses comparing non-shelled and shelled turtles indicate that the presence of the shell constrains humerus variation. Flippered aquatic turtles are released from this constraint and significantly increase overall disparity. Ontogenetic changes of turtle humeri are related to increased ossification and pronunciation of the proximal processes, the distal articulation areas, and the closure of the ectepicondylar groove to a foramen. Some turtle species retain juvenile features into adulthood and provide evidence for paedomorphic evolution. We review major changes of turtle humerus morphology throughout the evolution of its stem group."
THIS is an incredibly useful type of paper that we desperately need more of. Every bone in every living clade. Lizard femora, passeriform tarsometatarsi, marsupial dorsals, etc.. It's basic anatomical description made all that much easier by everything already being scanned. Instead we get so many new papers thrice removed from the actual data, examining the significance of the rate of evolutionary change based on a certain cladogram based on scoring that really could have used this basic data. Workers fifty years from now are not going to be caring about your conclusions on enantiornithine trophic trends based on a probably incorrect phylogeny, but everyone dealing with a turtle humerus is referencing Hermanson et al. 2024.
Mickey Mortimer
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