Morrison Formation: immature Camarasaurus anatomy + smallest Stegosaurus + Camptosaurus osteology atlas (free pdfs)
115 views
Skip to first unread message
Ben Creisler
Jan 23, 2026, 10:55:05 PM (10 days ago) Jan 23
to DinosaurMa...@googlegroups.com
Ben Creisler
More papers:
Free pdf:
Kenneth Carpenter, Takehito Ikejiri, and Yvonne Wilson (2026)
Postcranial anatomy of immature Camarasaurus specimens from Dinosaur National Monument, Utah, compared to the holotype of Camarasaurus lentus (Marsh, 1889)
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: 247-265
https://www.researchgate.net/publication/400035175_2026_Carpenter_et_al_Postcranial_anatomy_of_immature_Camarasaurus_specimens
The postcranial anatomy of two small, immature specimens of the Late Jurassic macronarian Camarasaurus lentus from the Morrison Formation at Dinosaur National Monument is described and compared with the holotype Camarasaurus lentus (Marsh, 1889) from Como Bluff, Wyoming. Both nearly complete skeletons exhibit a small body length (5.08 m and about 8 m respectively) for Morrison sauropods and hallmark characteristics of Camarasaurus, but they display distinct ontogenetic differences related to vertebral, girdle, and limb morphology. This comparison demonstrates progressive development of key anatomical features, particularly in fusion of the vertebral column and in limb robustness. We also compare the specimens with the holotype (body length about 6.11 m) of Camarasaurus lentus, to support the hypothesis that all three specimens represent the same taxonomic entity at different ontogenetic stages.
Free pdf:
Kenneth Carpenter (2026)
The smallest known Stegosaurus
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: 283-285
https://www.researchgate.net/publication/400035283_2026_Carpenter_Smallest_Stegosaurus
Juvenile dinosaur fossils are uncommon, and very small specimens of stegosaurs are particularly rare. This study describes skeletal remains of an exceptionally small stegosaur from the Morrison Formation, consisting of a partial right ilium, right tibia, a metatarsal, and two proximal pedal phalanges. The specimen, DMNH 33359, represents the smallest Stegosaurus currently known, with an estimated total length of approximately 1.5 meters. A detailed description of DMNH 33359 is presented and explores its significance in understanding Stegosaurus ontogeny by comparing it to the second smallest juvenile from Dinosaur National Monument and to adult specimens.
=====
The smallest known Stegosaurus
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: 283-285
https://www.researchgate.net/publication/400035283_2026_Carpenter_Smallest_Stegosaurus
Juvenile dinosaur fossils are uncommon, and very small specimens of stegosaurs are particularly rare. This study describes skeletal remains of an exceptionally small stegosaur from the Morrison Formation, consisting of a partial right ilium, right tibia, a metatarsal, and two proximal pedal phalanges. The specimen, DMNH 33359, represents the smallest Stegosaurus currently known, with an estimated total length of approximately 1.5 meters. A detailed description of DMNH 33359 is presented and explores its significance in understanding Stegosaurus ontogeny by comparing it to the second smallest juvenile from Dinosaur National Monument and to adult specimens.
=====
Free pdf:
Peter M. Galton and Kenneth Carpenter (2026)
Osteology atlas of the type materials in the Yale Peabody Museum of the ornithopod dinosaurian Camptosaurus dispar (Marsh, 1877) from the Upper Jurassic of Wyoming
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: 293-318
https://www.researchgate.net/publication/400035537_OSTEOLOGY_ATLAS_OF_THE_TYPE_MATERIALS_IN_THE_YALE_PAEABODY_MUSEUM_OF
The dinosaur genus Camptosaurus is a key taxon in the study of Late Jurassic ornithopod dinosaurs from the Morrison Formation of North America. Despite its historical and taxonomic significance, the holotype and paratype material of the type species, Camptosaurus dispar, has remained only superficially described since its naming by O.C. Marsh in 1879. Subsequent work by C.W. Gilmore focused heavily on a more complete referred specimen (USNM 4282) that he designated as the holotype of C. browni, leaving critical gaps in the anatomical understanding of the type specimens curated at the Yale Peabody Museum. The current study provides a comprehensive redescription of the C. dispar holotype (YPM VP 1877) and associated paratypes (YPM VP 1877a, 1878), as well as the holotype of C. medius (YPM VP 1880), which includes the only associated and partly articulated skull known from Quarry 13 at Como Bluff, Wyoming. The cranial anatomy of C. medius is described in detail for the first time using the fossil material and unpublished anatomical illustrations prepared under Marsh’s direction. These cranial elements, freed from a long-standing plaster reconstruction in the 1980s, are instrumental in reinterpreting key features of Camptosaurus skull morphology and correcting past taxonomic misattributions. Notably, the skull material attributed to C. amplus, now recognized as belonging to the iguanodontian Theiophytalia, is distinguished from the holotype skull of C. medius. This clarification is essential, as many previous reconstructions of Camptosaurus skulls were based on composite or misidentified
Peter M. Galton and Kenneth Carpenter (2026)
Osteology atlas of the type materials in the Yale Peabody Museum of the ornithopod dinosaurian Camptosaurus dispar (Marsh, 1877) from the Upper Jurassic of Wyoming
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: 293-318
https://www.researchgate.net/publication/400035537_OSTEOLOGY_ATLAS_OF_THE_TYPE_MATERIALS_IN_THE_YALE_PAEABODY_MUSEUM_OF
The dinosaur genus Camptosaurus is a key taxon in the study of Late Jurassic ornithopod dinosaurs from the Morrison Formation of North America. Despite its historical and taxonomic significance, the holotype and paratype material of the type species, Camptosaurus dispar, has remained only superficially described since its naming by O.C. Marsh in 1879. Subsequent work by C.W. Gilmore focused heavily on a more complete referred specimen (USNM 4282) that he designated as the holotype of C. browni, leaving critical gaps in the anatomical understanding of the type specimens curated at the Yale Peabody Museum. The current study provides a comprehensive redescription of the C. dispar holotype (YPM VP 1877) and associated paratypes (YPM VP 1877a, 1878), as well as the holotype of C. medius (YPM VP 1880), which includes the only associated and partly articulated skull known from Quarry 13 at Como Bluff, Wyoming. The cranial anatomy of C. medius is described in detail for the first time using the fossil material and unpublished anatomical illustrations prepared under Marsh’s direction. These cranial elements, freed from a long-standing plaster reconstruction in the 1980s, are instrumental in reinterpreting key features of Camptosaurus skull morphology and correcting past taxonomic misattributions. Notably, the skull material attributed to C. amplus, now recognized as belonging to the iguanodontian Theiophytalia, is distinguished from the holotype skull of C. medius. This clarification is essential, as many previous reconstructions of Camptosaurus skulls were based on composite or misidentified
Reply all
Reply to author
Forward
0 new messages