Hindlimb Osteology and Distribution of Basal Dinosauromorphs from the Late Triassic of North America

  title={Hindlimb Osteology and Distribution of Basal Dinosauromorphs from the Late Triassic of North America},
  author={Sterling J. Nesbitt and Randall B. Irmis and William G. Parker and Nathan D Smith and Alan H. Turner and Timothy B Rowe},
ABSTRACT The recent discovery of early dinosauromorphs from North America demonstrates that they were contemporaries with dinosaurs and other basal archosaurs during a substantial portion of the Late Triassic Period. Hindlimb material (femora, tibiae, a fibula, astragalocalcanea, and phalanges) of Dromomeron romeri, a non-dinosauriform dinosauromorph from the Petrified Forest Member of the Chinle Formation from north-central New Mexico, is described. A new species of Dromomeron from the lower… 
The Early Fossil Record of Dinosaurs in North America: A New Neotheropod from the Base of the Upper Triassic Dockum Group of Texas
Using the most comprehensive analysis of early theropod relationships currently available, it is determined that the new specimen represents one of the oldest neotheropods and was present at or just after the onset of both the Chinle Formation and Dockum Group deposits.
Non-dinosaurian dinosauromorphs from the Chinle Formation (Upper Triassic) of the Eagle Basin, northern Colorado: Dromomeron romeri (Lagerpetidae) and a new taxon, Kwanasaurus williamparkeri (Silesauridae)
The recognition of K. williamparkei further demonstrates the predominantly Late Triassic diversity and widespread geographic distribution across Pangea of the sister clade to Asilisaurus, here named Sulcimentisauria, and suggests a strong herbivorous dietary specialization among silesaurids.
The first pectoral and forelimb material assigned to the lagerpetid Lagerpeton chanarensis (Archosauria: Dinosauromorpha) from the upper portion of the Chañares Formation, Late Triassic
The first pectoral and forelimb bones of an avemetatarsalian from the upper portion of the Chanares Formation of Argentina are presented and it is hypothesize that the bones pertain to the important early ornithodiran Lagerpeton chanarensis, but the scapulocoracoid and humerus does not precisely match any non-dinosaurian ave Metatarsalian.
Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs
The parsimony analysis supports the basal position of L. admixtus within dinosauriforms, prior to the silesaurid–dinosaur split, rather than at the base of Silesauridae, and suggests that a higher number of early dinosauriform clades branched in the Middle and Late Triassic than previously suggested.
The osteology and systematic position of Dongusuchus efremovi Sennikov, 1988 from the Anisian (Middle Triassic) of Russia
A phylogenetic analysis recovers Dongusuchus efremovi as an early-diverging, non-archosaurian archosauriform and suggests that the limb morphology of Dongusucha may be plesiomorphic for Archosauria and proximal clades.
The Anatomy of Teleocrater rhadinus, an Early Avemetatarsalian from the Lower Portion of the Lifua Member of the Manda Beds (Middle Triassic)
ABSTRACT Bird-line archosaurs (= Avemetatarsalia, the clade containing birds, dinosaurs, pterosaurs, and their kin) originated in the Triassic Period. However, the earliest evolution of this group is
A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet
The Late Triassic dinosauromorph Sacisaurus agudoensis (Caturrita Formation; Rio Grande do Sul, Brazil): anatomy and affinities
Abstract Silesauridae is an exclusively Triassic group of dinosauromorphs, knowledge on the diversity of which has increased dramatically in the last few years. Silesaurid relationships are still
Osteology and relationships of Revueltosaurus callenderi (Archosauria: Suchia) from the Upper Triassic (Norian) Chinle Formation of Petrified Forest National Park, Arizona, United States.
Histology of the femur and associated osteoderms demonstrate that R. callenderi was slow growing and that the individuals from the bonebed were not young juveniles but had not ceased growing.
New Specimen Sheds Light on the Anatomy and Taxonomy of the Early Late Triassic Dinosauriforms from the Chañares Formation, NW Argentina
The morphology of the new specimen is completely congruent with that of specimens of Pseudolagosuchus major, bolstering the hypothesis that the latter species is a subjective junior synonym of Lewisuchus admixtus.


The osteology of the new small theropod dinosaur Masiakasaurus knopfleri, from the Late Cretaceous Maevarano Formation of northwestern Madagascar, suggests that these taxa form a clade (Noasauridae) within Abelisauroidea.
Dinosaurian precursors from the Middle Triassic of Argentina: Marasuchus lilloensis, gen. nov.
Several synapomorphies unite Marasuchus and dinosaurs (as Dinosauriformes) to the exclusion of the contemporary dinosauromorph Lagerpeton and pterosaurs.
Dinosaurian precursors from the Middle Triassic of Argentina: Lagerpeton chanarensis
There is no evidence that Lagerpeton and other small-bodied dinosauromorphs in the Los Chanares fauna, namely “Lagosuchus” lilloensis, comprise a monophyletic group.
The tibia and tarsus in Herrerasauridae (Dinosauria, incertae sedis) and the origin and evolution of the dinosaurian tarsus
  • F. Novas
  • Biology, Geography
    Journal of Paleontology
  • 1989
It is concluded that Herrerasauridae retained the primitive tibiotarsal condition for Dinosauria, from which those of the Ornithischia, Sauropodomorpha, and Theropoda were derived.
Scleromochlus taylori and the origin of dinosaurs and pterosaurs
A reanalysis of crown–group archosaur relationships confirms the split into Crurotarsi (crocodile relatives) and Ornithodira (bird relatives), as well as the clear division of Ornithadira into Pterosauria and Dinosauromorpha.
Osteology of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution
An in-depth morphological description of Cryolophosaurus is pre-sented here, along with a rigorous phylogenetic analysis of theropod relationships consisting of 347 characters and 56 taxa, in an attempt to clarify the relationships of Crylophosaurus and to provide insight into questions sur-rounding early theropid evolution.
A new species of the primitive dinosaur Thecodontosaurus (Saurischia: Sauropodomorpha) and its implications for the systematics of early dinosaurs
Synopsis Juvenile sauropodomorph specimens from a Late Triassic/Early Jurassic fissure fill in Pant‐y‐ffynnon Quarry, South Wales are redescribed and named as a new species, Thecodontosaurus caducus.
The skull and neck of the basal theropod Herrerasaurus ischigualastensis
The skull of Herrerasaurus ischigualastensis has a rectangular profile and a transversely narrow snout and other features of the skull constitute dinosaurian synapomorphies, such as the loss of the postfrontal and small post-temporal opening.
Coelophysids (Dinosauria: Theropoda) from the Upper Triassic (Revueltian) Snyder Quarry
The Snyder quarry preserves one of the richest assemblages of Norian theropods in the world, and the second-most productive theropod locality in the Chinle Group. At least four coelophysid theropods
  • J. Dzik
  • Environmental Science, Geography
  • 2003
Abstract An accumulation of skeletons of the pre-dinosaur Silesaurus opolensis, gen. et sp. nov. is described from the Keuper (Late Triassic) claystone of Krasiejów in southern Poland. The strata are