Chindesaurus bryansmalli
- 演化之聲
- 2 days ago
- 2 min read
Age
Triassic（Norian）
216 Ma
Taxonomy
Kingdom：Animalia
Phylum：Chordata
Class：Reptilia
Order：Saurischia
Genus：Chindesaurus
Species：Chindesaurus bryansmalli
Morphological description
Chindesaurus bryansmalli was a relatively small dinosaur, although its exact size remains uncertain due to the fragmentary nature of the fossils. Its body length has been estimated at approximately 2–4 meters, with a body mass of around 45 kilograms.
The anterior half of the lower margin of its cervical vertebrae bears a low ridge, while the lateral surfaces possess a pair of shallow oval depressions, features similar to those seen in other early theropod dinosaurs. Its dorsal vertebrae are tall and broad with relatively short centra, resembling those of herrerasaurids.
The femur was generally S-shaped, and the proximal end of the femur was smooth and nearly rectangular in outline, similar to that of Tawa.
Etymology
The genus name Chindesaurus is derived from Chinde Point, a landmark near the discovery site, combined with the common dinosaur suffix “-saurus,” meaning “lizard.”
The species name honors Bryan Small, who discovered the holotype specimen.
Biological interpretation
The holotype specimen of Chindesaurus bryansmalli was discovered in 1984 by Bryan Small in Petrified Forest National Park in northern Arizona, USA. The specimen, catalogued as PEFO 10395, consists mainly of fragmentary vertebrae, limb bones, and pelvic material. Although several additional specimens have been referred to the genus, only the holotype is confidently assigned to Chindesaurus.
The classification of Chindesaurus bryansmalli has long been controversial. When the specimen was first discovered in 1984, it was considered a basal sauropodomorph. However, when formally described in 1995, researchers interpreted it as a member of the Herrerasauridae, a conclusion later supported by many paleontologists and several phylogenetic analyses.
In 2017, another study instead suggested that Chindesaurus was a basal saurischian. Later, in 2021, a separate study proposed that it belonged to a non-herrerasaurid herrerasaurian lineage and formed a clade together with Tawa and Daemonosaurus. That same study also suggested that several fragmentary specimens previously assigned to Chindesaurus may not actually belong to the genus, but instead represent indeterminate members of the Chindesaurus–Tawa lineage.
Its habitat was a floodplain ecosystem inhabited by a diverse assemblage of terrestrial animals, along with several aquatic species.
（Author: Bai Leng）
Reference
1. Long, R. A., Murry, P. A. (1995). Late Triassic (Carnian and Norian) tetrapods from the Southwestern United States. New Mexico Museum of Natural History and Science Bulletin.
2. Marsh, A. D., Parker, W. G., Langer, M. C., Nesbitt, S. J. (2019). Redescription of the holotype specimen of Chindesaurus bryansmalli Long and Murry, 1995 (Dinosauria, Theropoda), from Petrified Forest National Park, Arizona. Journal of Vertebrate Paleontology.
3. Matthew G. B., Megan E. W. (2018). A re-evaluation of the enigmatic dinosauriform Caseosaurus crosbyensis from the Late Triassic of Texas, USA and its implications for early dinosaur evolution. Acta Palaeontologica Polonica.
4. Novas, F. E., Agnolin, F. L., Ezcurra, M. D., Temp Müller, R., Martinelli, A. G., Langer, M. C. (2021). Review of the fossil record of early dinosaurs from South America, and its phylogenetic implications. Journal of South American Earth Sciences.
5. Benson, R.B.J., Brusatte, S. (2012). Prehistoric Life. London: Dorling Kindersley.
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