Restoration of Eoraptor.
Vital statistics
Scientific Name Eoraptor
Length 1 meter
Height 30 centimeters
Weight 10 kilograms
Diet Carnivorous
Lived ca. 231 million years ago
Range Argentina

Eoraptor ("dawn thief"[1]) is one of the earliest known dinosaurs. It lived in the Late Triassic Period of Argentina.


Eoraptor measured approximately 1 meter in length, and is estimated to have weighed about 10 kilograms. It had lightly built bones, and in fact its leg bones were hollow.[2] Eoraptor had five digits on each hand, although the fourth and fifth digits were too small to be used regularly.

Classification and HistoryEdit

After being discovered in 1991 in the Ischigualasto Formation of Argentina, Eoraptor was described in 1993 by Paul Sereno and colleagues as one of the earliest dinosaurs.[3] Originally, it was described as a primitive theropod, a position supported by several subsequent studies.[4] However, it has also been suggested that Eoraptor is in fact a primitive sauropodomorph.[5] It is generally agreed that Eoraptor was an early saurischian, but a more precise classification is as yet uncertain.



Triassic Argentina was a warm and humid floodplain, subject to strong rainfall.[6][7] As such, the vegetation in the area was lush and diverse. Herrerasaurus and Pisanosaurus were dinosaur contemporaries of Eoraptor, and they lived with other reptiles such as rauisuchians, dicynodonts, and aetosaurs. These animals were much more common than early dinosaurs.[8]


Eoraptor is thought to have been an omnivore, eating both animals and plants. It had both curved, serrated teeth like theropods, and broad, leaf-shaped teeth like sauropodomorphs.[9]


  1. Liddell, Henry George and Robert Scott (1980). A Greek-English Lexicon (Abridged Edition). United Kingdom: Oxford University Press. ISBN 0-19-910207-4.
  2. Paul C. Sereno, Ricardo N. Martínez & Oscar A. Alcober (2013) Osteology of Eoraptor lunensis (Dinosauria, Sauropodomorpha). Basal sauropodomorphs and the vertebrate fossil record of the Ischigualasto Formation (Late Triassic: Carnian-Norian) of Argentina. Journal of Vertebrate Paleontology Memoir 12: 83-179 DOI:10.1080/02724634.2013.820113
  3. Sereno, P.C., Forster, C.A., Rogers, R.R., and Moneta, A.M. (1993). Primitive dinosaur skeleton form Argentina and the early evolution of the Dinosauria. Nature 361, 64-66.
  4. Bergman D.S., Sues H-D. (2011), "A late-surviving basal theropod dinosaur from the latest Triassic of North America", Proceedings of the Royal Society B, published online 13-4-2011.
  5. R.N. Martinez et al. A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. Science, Vol. 331, January 14, 2011, p. 206.
  6. Tucker, Maurice E.; Benton, Michael J. (1982). "Triassic environments, climates, and reptile evolution". Palaeogeography, Palaeoclimatology, Palaeoecology 40 (4): 361–379. doi:10.1016/0031-0182(82)90034-7. Retrieved 2009-07-23.
  7. Columbi, Carina E. (2008-10-05). "Stable isotope analysis of fossil plants from the Upper Triassic Ischigualasto Formation in the northwest of Argentina". Houston, TX: The Geological Society of America. Retrieved 2009-07-23.
  8. Bonaparte, J.F. (1970). "Annotated list of the South American Triassic tetrapods". Gondwana Symposium Proceedings and Papers 2: 665–682.
  9. Paul G.S., The Princeton Field Guide to Dinosaurs (Princeton University Press, 2010), p. 68.