Eoraptor
From Greek eos, 'dawn', + Latin raptor, 'seizer/thief'; means 'dawn thief' or 'dawn plunderer', reflecting its status as one of the earliest known dinosaurs
Eoraptor is a genus of small, lightly built, basal sauropodomorph dinosaur. One of the earliest-known dinosaurs and one of the earliest sauropodomorphs, it lived approximately 231 to 228 million years ago, during the Late Triassic in Western Gondwana, in the region that is now northwestern Argentina. The type and only species, Eoraptor lunensis, was first described in 1993, and is known from an almost complete and well-preserved skeleton and several fragmentary ones. Eoraptor had multiple tooth shapes, which suggests that it was omnivorous.
Under dispute
Eoraptor lunensis was originally described as a basal theropod (Sereno and colleagues, 1993) and later recovered as a basal saurischian outside both Theropoda and Sauropodomorpha (Langer, 2004). Most analyses since its 2012 redescription recover it as a basal sauropodomorph (Martínez and colleagues, 2012; Sereno and colleagues, 2013).
Diagnosis
- Premaxilla with a slender posterolateral process bearing a tongue-shaped distal expansion.
- Nasal with a transversely broad, horizontal shelf with a convex lateral margin that overhangs the antorbital fossa.
- Pterygoid process on the posterior palate margin that articulates laterally in a synovial socket in the ectopterygoid.
- Narrow premaxilla-maxilla diastema, approximately one crown in width.
- Maxillary crowns with a prominent lateral eminence.
- Accessory articular process on the medial aspect of the midcervical prezygapophyses.
- Extreme hollowing of the dorsal centra and neural arches.
Species
Eoraptor lunensis Sereno et al., 1993
Type species
From Latin 'luna' meaning 'moon' with the suffix '-ensis' meaning 'from', a reference to the Valle de la Luna ('Valley of the Moon') in Argentina where the holotype was found.
- Holotype
- PVSJ 512 , División de Paleontología de Vertebrados del Museo de Ciencias Naturales y Universidad Nacional de San Juan
- Material
- Articulated skeleton lacking portions of the left side of the skull, the caudal vertebrae distal to caudal 17, most of the left scapula, the left coracoid, the left manual unguals, and the distal two phalanges of right pedal digit III.
- Horizon
- Cancha de Bochas Member, Ischigualasto Formation, Carnian, Late Triassic , 237.0–227.3 million years ago
- Locality
- northeastern edge of Cancha de Bochas, San Juan, Argentina
References
- Sereno, P. C.; Forster, C. A.; Rogers, R. R.; Monetta, A. M. (1993). Primitive dinosaur skeleton from Argentina and the early evolution of Dinosauria. Nature 361(6407): 64-66. Springer Science and Business Media LLC. doi:10.1038/361064a0 sereno1993a
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Sereno, P. C.; Martínez, R. N.; Alcober, O. A. (2013). Osteology of Eoraptor lunensis (Dinosauria, Sauropodomorpha). Journal of Vertebrate Paleontology Memoir 12: 83-179. Informa UK Limited. doi:10.1080/02724634.2013.820113
Comprehensive osteological redescription of the holotype PVSJ 512; supports Eoraptor as a basal sauropodomorph and provides a revised diagnosis.
sereno2013a -
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.
Source of the hip height estimate.
jones2026b -
Martínez, R. N.; Apaldetti, C.; Abelín, D. (2012). Basal sauropodomorphs from the Ischigualasto Formation. Journal of Vertebrate Paleontology 32(sup1): 51-69. doi:10.1080/02724634.2013.819361
Redescribed Eoraptor and recovered it as a basal sauropodomorph rather than a basal theropod
martínez2012a -
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
Recovered Eoraptor with the herrerasaurids at the base of Saurischia, outside Theropoda and Sauropodomorpha.
langer2004a