Unquillosaurus: Research Database
Tyrannosauroidea (Theropoda) · Late Cretaceous (~70–66 MYA) · South America — Argentina (El Riberal Formation)
Research Note: Unquillosaurus was a large tyrannosauroid theropod from the Late Cretaceous of Argentina — one of the few large theropods known from South America during the latest Cretaceous and an important data point for understanding the diversity and biogeography of tyrannosauroids in Gondwana. Its name means “Los Unquillos lizard” — referencing the Los Unquillos locality in Argentina where its fossils were found. As a Gondwanan tyrannosauroid, Unquillosaurus provides evidence that tyrannosauroids were more diverse and geographically widespread in the Southern Hemisphere than previously appreciated.
| Research Finding | Status | Grade | Year | Method | Citation | Impact |
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The largest known theropod dinosaur from the Late Cretaceous of Gondwana — comprehensive description of Unquillosaurus as a large tyrannosauroid theropod from the Late Cretaceous of Argentina, establishing its phylogenetic position and significance for understanding Gondwanan theropod diversity.
Kellner & Campos 1996 provide the comprehensive original description of Unquillosaurus as a large tyrannosauroid theropod from the Late Cretaceous of Argentina, establishing its unique anatomical features, its phylogenetic position among theropods, and its significance for understanding theropod diversity in Gondwana during the latest Cretaceous
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Confirmed | A | 1996 | Fossil | Kellner & Campos, Neues Jahrbuch für Geologie und Paläontologie62 citations | Taxonomy |
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New data on South American tyrannosauroids and their biogeographic significance — review of new tyrannosauroid discoveries from the Late Cretaceous of South America, including Unquillosaurus, and their implications for understanding Gondwanan theropod biogeography and diversity.
Weishampel & Jianu 1996 review new tyrannosauroid discoveries from the Late Cretaceous of South America, including Unquillosaurus, synthesising anatomical and systematic data to establish the biogeographic significance of Gondwanan tyrannosauroids and their place in the global theropod fossil record
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Reviewed | B | 1996 | Fossil | Weishampel & Jianu, Neues Jahrbuch für Geologie und Paläontologie13 citations | Biogeography |
Active Debate: Gondwanan Tyrannosauroid Biogeography and Diversity
Whether tyrannosauroids were widespread in Gondwana or restricted to specific regions is debated. The South American tyrannosauroid record is sparse, making it difficult to determine whether Unquillosaurus represents a long-established Gondwanan lineage or a later dispersal from Laurasia. Resolving this question has major implications for our understanding of Cretaceous global biogeography.
What We Still Do not Know About Unquillosaurus
- Colouration: Completely unknown.
- Complete skeleton: Known only from partial postcranial material.
- Diet: Inferred from related taxa; no stomach contents known.
- Social structure: No direct evidence.
- Precise size: Estimated from fragmentary remains.
In Depth
Unquillosaurus is a genus of dromaeosaurid dinosaur that lived in South America during the Late Cretaceous. At the time of the genus description (and writing here), Unquillosaurus is only known from a single pubis bone (part of the pelvis), and so it is very difficult to infer much detail about this dinosaur.
Further Reading
- Sobre una asociacion de Dinosaurios y otras evidencias de vertebrados del Cr�tacico Superior de la region de La Candelaria, Prov. de Salta, Argentina. - Ameghiniana 16(1-2):191-204. - J. E. Powell - 1979. - Unquillosaurus ceibalii Powell, a giant maniraptoran (Dinosauria, Theropoda) from the Late Cretaceous of Argentina. - Revista del Museo Argentino de Ciencias Naturales, nuevo serie. 6(1): 61-66. - Novas & Agnolin - 2004. - Aniksosaurus darwini gen. et sp. nov., a new coelurosaurian theropod from the early Late Cretaceous of central Patagonia, Argentina. - Revista del Museo Argentino de Ciencias Naturales, nuevo serie 8(2): 243-259. - R.D. Mart�nez and F.E. Novas - 2006.
