Morrison Formation: Dystrophaeus type locality + Amblotherium apiarium, new dryolestid + Eilenodon (sphenodontid) new material (free pdfs)
75 views
Skip to first unread message
Ben Creisler
Jan 23, 2026, 1:06:58 PM (10 days ago) Jan 23
to DinosaurMa...@googlegroups.com
Ben Creisler
Thanks to Jerry for posting the turiasaur paper.
More papers from the new Morrison Formation volume:
John R. Foster, Kelli C. Trujillo, Randall B. Irmis, Mathew J. Wedel, Kevin R. Chamberlain, David D. Gillette, and Sharon K. McMullen (2026)
History, age, and stratigraphy of the type locality of Dystrophaeus viaemalae (Sauropoda) in the lower Morrison Formation of southeastern Utah
In: Foster et al., 2026, New Developments in the Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 102: 201-213
https://www.researchgate.net/publication/399997614_HISTORY_AGE_AND_STRATIGRAPHY_OF_THE_TYPE_LOCALITY_OF_DYSTROPHAEUS_VIAEMALAE_SAUROPODA_IN_THE_LOWER_MORRISON_FORMATION_OF_SOUTHEASTERN_UTAH
To the holotype of the enigmatic Late Jurassic sauropod Dystrophaeus viaemalae (Tidwell Member, Morrison Formation, Utah) we add more elements of the same associated and partially articulated skeleton under UMNH 24959. This individual was previously known from a scapula fragment, an ulna, half a radius, and three metacarpals. To this we add, so far, two teeth, four dorsal and two caudal vertebrae, dorsal ribs, metacarpal, ilium fragments including pubic peduncle, fibula, astragalus, metatarsal, phalanx, and many fragments (collected 2014–2023). This preliminary assessment, to be followed by full description later, suggests that Dystrophaeus is not a diplodocoid. The age of the specimen is estimated as 156.1±2.1 Ma (late Oxfordian).
====
Brigid E. Connelly, Guillermo W. Rougier, and Brian M. Davis (2026)
Associated upper and lower dentition of a new species of the dryolestid mammal Amblotherium from the Upper Jurassic Morrison Formation (Utah, USA)
In: Foster et al., 2026, New Developments in the Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 102: 331-345
https://www.researchgate.net/publication/400024668_ASSOCIATED_UPPER_AND_LOWER_DENTITION_OF_A_NEW_SPECIES_OF_THE_DRYOLESTID_MAMMAL_AMBLOTHERIUM_FROM_THE_UPPER_JURASSIC_MORRISON_FORMATION_UTAH_USA
Amblotherium Owen, 1871 is one of the most speciose dryolestid genera, mainly represented by isolated teeth and jaw fragments from the Upper Jurassic Morrison Formation and the Lower Cretaceous Purbeck Group. With a relatively generalized lower dentition and a paucity of associated material, species of this genus have been variously synonymized. Here, we describe a new species, Amblotherium apiarium sp. nov., based on the dentition of an associated dentary and maxilla recovered from the Cisco Mammal Quarry (Morrison Formation, eastern Utah). Data from this new specimen inform a revised diagnosis of the genus, clarifying species recognition and validity. This new taxon adds to the growing diversity from the Cisco Mammal Quarry and underscores the value of additional collection efforts, even in units as heavily sampled as the Morrison Formation.
Yara Haridy, Joseph A. Frederickson, Joseph Peterson, Jordan Miller, Brian Davis, Brian Curtice, Rick Hunter, and Richard Cifelli (2026)
New material of the Late Jurassic sphenodontid Eilenodon robustus reveals transitionary adaptations to herbivory
In: Foster et al., 2026, New Developments in the Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 102: 171-184
https://www.researchgate.net/publication/400003504_NEW_MATERIAL_OF_THE_LATE_JURASSIC_SPHENODONTID_EILENODON_ROBUSTUS_REVEALS_TRANSITIONARY_ADAPTATIONS_TO_HERBIVORY
Sphenodontians were relatively common in the fauna of the Upper Jurassic Morrison Formation of western North America. A once diverse group, today sphenodontians are only represented by the tuatara (Sphenodon punctatus). Currently, four sphenodontian genera are recognized from the Morrison Formation, with multiple of these species described largely based on jaw and tooth morphology. Here, we describe three new specimens of the poorly known Eilenodon robustus from two disparate localities in the Morrison Formation. This large-bodied species is easily distinguished from other sphenodontians from the Jurassic of North America based on its unique dentition seemingly adapted for an herbivorous lifestyle. Beyond skeletal robustness and a few novel features, the new specimens do not depart greatly from the general sphenodontian body plan and indicate that Eilenodon robustus would have had a similar ground-dwelling lifestyle to its modern counterpart. Importantly, histological analysis of femora from two individuals reveals up to ten lines of arrested growth (LAGs), with widely spaced early lines indicative of an initially faster growth rate than in the modern tuatara. Additionally, high-resolution micro-CT scanning and virtual segmentation provide the first three-dimensional reconstructions of the cranial anatomy of Eilenodon and the first detailed tooth row histology for the taxon, highlighting transitional adaptations toward herbivory.
=====
Free pdf:
John R. Foster, Kelli C. Trujillo, Randall B. Irmis, Mathew J. Wedel, Kevin R. Chamberlain, David D. Gillette, and Sharon K. McMullen (2026)
History, age, and stratigraphy of the type locality of Dystrophaeus viaemalae (Sauropoda) in the lower Morrison Formation of southeastern Utah
In: Foster et al., 2026, New Developments in the Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 102: 201-213
https://www.researchgate.net/publication/399997614_HISTORY_AGE_AND_STRATIGRAPHY_OF_THE_TYPE_LOCALITY_OF_DYSTROPHAEUS_VIAEMALAE_SAUROPODA_IN_THE_LOWER_MORRISON_FORMATION_OF_SOUTHEASTERN_UTAH
To the holotype of the enigmatic Late Jurassic sauropod Dystrophaeus viaemalae (Tidwell Member, Morrison Formation, Utah) we add more elements of the same associated and partially articulated skeleton under UMNH 24959. This individual was previously known from a scapula fragment, an ulna, half a radius, and three metacarpals. To this we add, so far, two teeth, four dorsal and two caudal vertebrae, dorsal ribs, metacarpal, ilium fragments including pubic peduncle, fibula, astragalus, metatarsal, phalanx, and many fragments (collected 2014–2023). This preliminary assessment, to be followed by full description later, suggests that Dystrophaeus is not a diplodocoid. The age of the specimen is estimated as 156.1±2.1 Ma (late Oxfordian).
====
Free pdf:
Amblotherium apiarium sp. nov.
Brigid E. Connelly, Guillermo W. Rougier, and Brian M. Davis (2026)
Associated upper and lower dentition of a new species of the dryolestid mammal Amblotherium from the Upper Jurassic Morrison Formation (Utah, USA)
In: Foster et al., 2026, New Developments in the Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 102: 331-345
https://www.researchgate.net/publication/400024668_ASSOCIATED_UPPER_AND_LOWER_DENTITION_OF_A_NEW_SPECIES_OF_THE_DRYOLESTID_MAMMAL_AMBLOTHERIUM_FROM_THE_UPPER_JURASSIC_MORRISON_FORMATION_UTAH_USA
Amblotherium Owen, 1871 is one of the most speciose dryolestid genera, mainly represented by isolated teeth and jaw fragments from the Upper Jurassic Morrison Formation and the Lower Cretaceous Purbeck Group. With a relatively generalized lower dentition and a paucity of associated material, species of this genus have been variously synonymized. Here, we describe a new species, Amblotherium apiarium sp. nov., based on the dentition of an associated dentary and maxilla recovered from the Cisco Mammal Quarry (Morrison Formation, eastern Utah). Data from this new specimen inform a revised diagnosis of the genus, clarifying species recognition and validity. This new taxon adds to the growing diversity from the Cisco Mammal Quarry and underscores the value of additional collection efforts, even in units as heavily sampled as the Morrison Formation.
====
Free pdf:
Yara Haridy, Joseph A. Frederickson, Joseph Peterson, Jordan Miller, Brian Davis, Brian Curtice, Rick Hunter, and Richard Cifelli (2026)
New material of the Late Jurassic sphenodontid Eilenodon robustus reveals transitionary adaptations to herbivory
In: Foster et al., 2026, New Developments in the Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 102: 171-184
https://www.researchgate.net/publication/400003504_NEW_MATERIAL_OF_THE_LATE_JURASSIC_SPHENODONTID_EILENODON_ROBUSTUS_REVEALS_TRANSITIONARY_ADAPTATIONS_TO_HERBIVORY
Sphenodontians were relatively common in the fauna of the Upper Jurassic Morrison Formation of western North America. A once diverse group, today sphenodontians are only represented by the tuatara (Sphenodon punctatus). Currently, four sphenodontian genera are recognized from the Morrison Formation, with multiple of these species described largely based on jaw and tooth morphology. Here, we describe three new specimens of the poorly known Eilenodon robustus from two disparate localities in the Morrison Formation. This large-bodied species is easily distinguished from other sphenodontians from the Jurassic of North America based on its unique dentition seemingly adapted for an herbivorous lifestyle. Beyond skeletal robustness and a few novel features, the new specimens do not depart greatly from the general sphenodontian body plan and indicate that Eilenodon robustus would have had a similar ground-dwelling lifestyle to its modern counterpart. Importantly, histological analysis of femora from two individuals reveals up to ten lines of arrested growth (LAGs), with widely spaced early lines indicative of an initially faster growth rate than in the modern tuatara. Additionally, high-resolution micro-CT scanning and virtual segmentation provide the first three-dimensional reconstructions of the cranial anatomy of Eilenodon and the first detailed tooth row histology for the taxon, highlighting transitional adaptations toward herbivory.
=====
Reply all
Reply to author
Forward
0 new messages