Herrerasauria
Herrerasauria is a clade of carnivorous dinosaurs from the Late Triassic, among the oldest dinosaurs known, first appearing roughly 233 million years ago during the Carnian stage. Its best-known members come from South America, including Herrerasaurus and Staurikosaurus of Argentina and Brazil, though possible relatives have also been recovered in North America, Africa, and perhaps other continents. Most were small to mid-sized predators, typically no more than about 4 meters long. Their anatomy blends primitive and derived features: they only superficially resemble later theropods and are not thought to be ancestral to any later dinosaur group. Distinctive traits include a hip socket that is only partly open, just two sacral vertebrae (the fewest of any dinosaur), and a hinged lower jaw. Their exact position on the dinosaur family tree remains debated, with analyses variously placing them as basal saurischians that diverged before the split between theropods and sauropodomorphs, or as early theropods.
Under dispute
The scope of Herrerasauria is unsettled. Recent analyses recover it as a clade broader than Herrerasauridae: Ezcurra and colleagues (2025) place Maleriraptor in it outside Herrerasauridae, and Novas and colleagues (2021) and Srivastava and Nesbitt (2026) include the Tawa-Chindesaurus-Daemonosaurus group, which Srivastava and Nesbitt name Morphoraptora. The Princeton Encyclopedia (Jones, 2026) uses Herrerasauria as another name for Herrerasauridae. Its position is also contested: most analyses place it within Saurischia outside the clade of theropods and sauropodomorphs (Langer, 2004; Novas and colleagues, 2021; Ezcurra and colleagues, 2025), others recover herrerasaurids at the base of Theropoda (Nesbitt and colleagues, 2009; Sues and colleagues, 2011) or as the sister of Sauropodomorpha (Baron and colleagues, 2017), and Baron and Williams (2018) place Herrerasauria outside Dinosauria.
Diagnosis
- Predatory dentition with recurved, serrated, laterally compressed teeth
- Grasping, elongate manus with reduced outer digits
- Elongate, distally expanded pubis
Clades within Herrerasauria
- Herrerasauridae 4 genera
Genera placed directly in Herrerasauria
- Caseosaurus Disputed Carnian–Norian (237.0–205.7 Ma)United States
- Maleriraptor Norian (227.3–205.7 Ma)Indiaunder dispute
- Ptychotherates Norian–Rhaetian (227.3–201.4 Ma)United Statesunder dispute
References
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Galton, P. M. (1985). The poposaurid thecodontian Teratosaurus suevicus v. Meyer, plus referred specimens mostly based on prosauropod dinosaurs, from the Middle Stubensandstein (Upper Triassic) of Nordwürttemberg. Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie) 116: 1-29.
Source in which the name Herrerasauria was proposed.
galton1985c -
Langer, M. C. (2004). Basal Saurischia. The Dinosauria, Second Edition (Weishampel, D. B.; Dodson, P.; Osmólska, H., eds.) 25-46. University of California Press, Berkeley. doi:10.1525/california/9780520242098.003.0004
Provided the phylogenetic definition of Herrerasauria used for the clade.
langer2004a -
Ezcurra, M. D.; Garcia, M. S.; Novas, F. E.; Müller, R. T.; Agnolín, F. L.; Chatterjee, S. (2025). A new herrerasaurian dinosaur from the Upper Triassic Upper Maleri Formation of south-central India. Royal Society Open Science 12(5): 250081. The Royal Society. doi:10.1098/rsos.250081
New herrerasaurian description with phylogeny recovering a broader Herrerasauria distinct from Herrerasauridae.
ezcurra2025a -
Srivastava, S.; Nesbitt, S. J. (2026). A new taxon of saurischian dinosaur from the Coelophysis Quarry of New Mexico, USA (Triassic: latest Norian or Rhaetian) highlights herrerasaurian diversity in the latest Triassic. Papers in Palaeontology 12(2). doi:10.1002/spp2.70069
New saurischian description with phylogeny recovering a broader Herrerasauria scope.
srivastava2026a -
Novas, F. E.; Agnolín, F. L.; Ezcurra, M. D.; Müller, R. T.; 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 110: 103341. doi:10.1016/j.jsames.2021.103341
Recovered Herrerasauria as a broader clade outside Eusaurischia, and summarizes the three hypotheses for its position.
novas2021a -
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.
Uses Herrerasauria as another name for Herrerasauridae, placed within Saurischia but outside Theropoda.
jones2026c -
Nesbitt, S. J.; Smith, N. D.; Irmis, R. B.; Turner, A. H.; Downs, A.; Norell, M. A. (2009). A Complete Skeleton of a Late Triassic Saurischian and the Early Evolution of Dinosaurs. Science 326(5959): 1530-1533. American Association for the Advancement of Science (AAAS). doi:10.1126/science.1180350
Recovered Herrerasauridae at the base of Theropoda, with weak support.
nesbitt2009a -
Sues, H. D.; Nesbitt, S. J.; Berman, D. S.; Henrici, A. C. (2011). A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society B: Biological Sciences 278(1723): 3459-3464. The Royal Society. doi:10.1098/rspb.2011.0410
Supported a basal theropod position for herrerasaurids rather than a basal saurischian one.
sues2011a -
Baron, M. G.; Norman, D. B.; Barrett, P. M. (2017). A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543(7646): 501-506. doi:10.1038/nature21700
Recovered Herrerasauridae as the sister of Sauropodomorpha in a redefined Saurischia.
baron2017a -
Baron, M. G.; Williams, M. E. (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 63(1): 129-145. Polish Academy of Sciences. doi:10.4202/app.00372.2017
Recovered Herrerasauria outside Dinosauria on the dataset of Baron and colleagues (2017).
baron2018c