Aucasaurus
Type species Aucasaurus garridoi
- Lived
- 84 to 72 million years ago, Late Cretaceous
- Diet
- Carnivore
- Length
- about 5 m (16 ft)
- Group
- Theropods, Abelisauridae
- Found in
- Argentina
- Named by
- Coria et al. 2002
Size comparison
To scale
Scale in metersOutline: typical theropod shape
Where its fossils were found
The evidence
Today
80 million years ago
Habitat
River plains in Argentina supported large plant eaters such as Neuquensaurus and Antarctosaurus, alongside the smaller Gasparinisaura.
Field notes
About Aucasaurus
What it was like
Aucasaurus was an abelisaurid, a two-legged meat eater with a short, deep skull and tiny arms. It was about 5 meters (16 feet) long, smaller than its close relative Carnotaurus.
Its arms were even more reduced than those of Carnotaurus, with barely any fingers. Its skeleton is one of the most complete of its family.
Its world
It lived about 84 to 72 million years ago, in the Late Cretaceous, in what is now Argentina. Its bones come from the Anacleto Formation, a place famous for huge nesting grounds of titanosaurs. It lived beside the megaraptoran Aerosteon, the small plant eater Gasparinisaura and titanosaurs such as Neuquensaurus.
How it was found
Coria and colleagues named Aucasaurus in 2002. The type species is Aucasaurus garridoi. The one known skeleton has a damaged skull, which some scientists think may be an injury from a fight.
Field gallery
More views of Aucasaurus
Scenes reconstructed from the available fossil evidence.
1 of 3
Lived alongside
Found in the same rock formations
A rock formation can hold fossils laid down millions of years apart, so not every animal here met Aucasaurus.
The evidence
The science behind Aucasaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- A nearly complete skeleton includes parts of the skull, backbone and tail, along with almost complete arms and legs.
- Its tiny hands had greatly reduced fingers.
- Air-filled spaces inside some tail vertebrae connected to its air-sac system.
Borrowed from relatives
- Most of the body is restored from its own bones, with Carnotaurus helping fill gaps in the damaged skull and missing tail tip.
Still unknown
- Its color and skin pattern.
- Whether it hunted alone or in groups.
- What its hatchlings looked like.
Discovery timeline
- 2002Named itCoria, Chiappe & Dingus
- 2011SkullPAULINA CARABAJAL
- 2023Full descriptionBaiano et al.
Key papers
The research behind what we know of Aucasaurus
Named it
Named a close relative of Carnotaurus from a nearly complete skeleton with tiny arms and greatly reduced fingers.
A new close relative ofCarnotaurus sastreiBonaparte 1985 (Theropoda: Abelisauridae) from the Late Cretaceous of Patagonia. Journal of Vertebrate Paleontology 22: 460-465
Read the paper : A new close relative ofCarnotaurus sastreiBonaparte 1985 (Theropoda: Abelisauridae) from the Late Cretaceous of Patagonia (opens in a new tab)Skull
Compared the braincases of Aucasaurus and Abelisaurus, revealing shared features and differences within their family.
Braincases of abelisaurid theropods from the Upper Cretaceous of north Patagonia. Palaeontology 54: 793-806
Read the paper : Braincases of abelisaurid theropods from the Upper Cretaceous of north Patagonia (opens in a new tab)Full description
Described the backbone and tail, finding air-filled spaces in tail bones and attachments that probably helped stiffen the body.
Osteology of the axial skeleton of Aucasaurus garridoi: phylogenetic and paleobiological inferences. PeerJ 11: e16236
Read the paper : Osteology of the axial skeleton of Aucasaurus garridoi: phylogenetic and paleobiological inferences (opens in a new tab)
Close relatives
Other members of Abelisauridae
Sources: Wikidata