Herrerasaurus: Research Database
Herrerasauridae (Theropoda) · Late Triassic (~231-228 MYA) · South America — Argentina (Ischigualasto-Villa Union Basin)
Research Note: Herrerasaurus was one of the earliest known dinosaurs from the Late Triassic of Argentina — a herrerasaurid theropod that provides crucial data on the early diversification of dinosaurs. As one of the most primitive known theropods, it offers insights into the origin of Dinosauria.
| Research Finding | Status | Grade | Year | Method | Citation | Impact |
|---|---|---|---|---|---|---|
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Sereno et al. 1992: Herrerasaurus and the origin of Dinosauria
Sereno et al. 1992 provide comprehensive data on Herrerasaurus from the Late Triassic of Argentina, establishing it as one of the earliest known dinosaurs and documenting the origin of Dinosauria
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Confirmed | A | 1992 | Fossil | Sereno et al., Nature | Taxonomy |
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Novas 1993: Herrerasaurus and new data on early dinosaur evolution
Novas 1993 provides additional data on Herrerasaurus and early dinosaur evolution, further contextualising its significance within Theropoda
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Confirmed | B | 1993 | Fossil | Novas, Journal of Vertebrate Paleontology | Evolution |
Active Debate: The Origin of Dinosaurs, Triassic Ecosystem Dynamics
Whether Herrerasaurus was more closely related to theropods or to sauropodomorphs is debated. Its primitive position near the base of Dinosauria makes it crucial for understanding the early diversification of dinosaurs.
The Late Triassic extinction — and the role it played in allowing dinosaurs to become dominant — is a major question in paleontology.
What We Still Do Not Know About Herrerasaurus
- Precise phylogenetic position: Debated; near base of Theropoda.
- Diet: Likely carnivorous.
- Social behavior: No direct evidence.
- Body size: Moderate; known.
In Depth
In 1941 an alligator specimen from the Green River Formation was interpreted as being a new species of Hassiacosuchus by C. C. Mook. However a later 1967 study by Wassersug and Hecht found the remains of the second species actually belonged within the Procaimanoidea genus, and as such the second species of Hassiacosuchus became the second species of Procaimanoidea. This also makes Hassiacosuchus a distinctly European genus, however its future as a distinct genus is in doubt. Later studies have suggested that Hassiacosuchus may in fact belong within another North American genus called Allognathosuchus, although in 2004 another study by Christopher Brochu has led to the recommendation that Hassiacosuchus remain a distinct genus.
Further Reading
– Hassiacosuchus haupti n. g. n. sp., ein durophages Krokodil aus dem Mitteleoz�n von Messel – Notizblatt des Vereins f�r Erdkunde und der Hessischen Geologischen Landesanstalt Darmstadt (in German) 16: 40–49. – K. Weitzel – 1935. – The status of the crocodylid genera Procaimanoidea and Hassiacosuchus in the New World – Herpetologica 23 (1): 30–34. – R. J. Wassersug – 1967.
