Open Paleo

Herrerasauridae

Benedetto, 1973 Type genus Herrerasaurus

Its genera lived 237.0–227.3 million years ago Late Triassic
Late Triassic stages

Herrerasauridae is a family of early carnivorous dinosaurs from the Late Triassic (Carnian to Norian) of South America, with more fragmentary possible members reported from North America, Africa, and Europe. They are among the oldest known dinosaurs, appearing in the fossil record around 233 million years ago. The best-known members — Herrerasaurus and Sanjuansaurus from Argentina and Staurikosaurus and Gnathovorax from Brazil — were bipedal predators; most were relatively small, generally no more than about four meters long, though the largest reached roughly six meters. Herrerasaurid anatomy is unusual and specialized, mixing very primitive and derived traits, and the group is not thought to be ancestral to any later dinosaur lineage. They only superficially resemble the theropods, sharing three-fingered grasping hands with curved claws and a hinged lower jaw while retaining a number of more primitive features.

Under dispute

The position of Herrerasauridae is long contested: it has been recovered as a basal theropod (Nesbitt and colleagues, 2009), as the sister group of Sauropodomorpha (Baron and colleagues, 2017), as the sister group of the sauropodomorph-theropod clade (Novas and colleagues, 2021), and (Baron and Williams, 2018) even outside Dinosauria. Its unambiguous record long consisted of Herrerasaurus, Sanjuansaurus, Staurikosaurus and Gnathovorax, while Chindesaurus is a herrerasaur in some analyses but not in others (Ezcurra and colleagues, 2025).

Diagnosis

  1. Intramandibular joint between the dentary and postdentary bones allowing the lower jaw to flex
  2. Elongate, functionally tridactyl manus bearing large recurved trenchant claws
  3. Partly opisthopubic pelvis with an elongate, distally expanded pubis
  4. Only two sacral vertebrae

Genera placed directly in Herrerasauridae

  • Gnathovorax Pacheco et al., 2019 Carnian (237.0–227.3 Ma)Brazil
  • Herrerasaurus Reig, 1963 Carnian (237.0–227.3 Ma)Argentina
  • Sanjuansaurus Alcober & Martínez, 2010 Carnian (237.0–227.3 Ma)Argentina
  • Staurikosaurus Colbert, 1970 Carnian (237.0–227.3 Ma)Brazil

References

  1. Benedetto, J. L. (1973). Herrerasauridae, nueva familia de Saurisquios Triasicos [Herrerasauridae, New Family of Triassic Saurischians]. Ameghiniana 10: 89-102.

    Original proposal of the family Herrerasauridae.

    benedetto1973a
  2. Novas, F. E. (1992). Phylogenetic relationships of the basal dinosaurs, the Herrerasauridae. Palaeontology 35: 51-62.

    Provided the phylogenetic definition of Herrerasauridae used for the clade.

    novas1992a
  3. 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

    Herrerasaurian analysis supporting placement within Saurischia outside Theropoda.

    ezcurra2025a
  4. 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

    Recent herrerasaurian analysis supporting placement within Saurischia outside Theropoda

    novas2021a
  5. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Places Herrerasauridae within Saurischia but outside Theropoda as its least contentious position, noting placements within Theropoda or as sister to Sauropodomorpha.

    jones2026c
  6. 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

    Assessed Caseosaurus and its implications for early herrerasaurian evolution.

    baron2018c
  7. 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

    Described Tawa and recovered Herrerasauridae, with Staurikosaurus and Chindesaurus, at the base of Theropoda with weak support.

    nesbitt2009a
  8. 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

    Proposed Ornithoscelida and recovered Herrerasauridae as the sister clade of Sauropodomorpha.

    baron2017a