Dinosaurs A to Z
Ceratosauria

Carnotaurus sastrei KAR-no-TOR-us

"Meat-eating bull"

Carnotaurus silhouette
You 1.8 m (5.9 ft) tall
Carnotaurus 8 m (26.2 ft) long
as long as 5 people standing fingertip to fingertip
silhouette · thetruespinofanboi (CC0) via PhyloPic
Length
8 m (26.2 ft) — About 8 m long, ~1.6 tonnes — fast-running with tiny vestigial arms.
Period
Late Cretaceous (72–69 Mya)
Place
South America · Argentina
Food
Carnivore — Medium-sized prey, probably caught at high speed — long legs and a streamlined body.
Clade
Ceratosauria Dinosauria Saurischia Theropoda Horned theropods: Ceratosaurus, Carnotaurus.

A horned, short-armed Cretaceous predator from Argentina, possibly one of the fastest big theropods.

Carnotaurus had two short bull-like horns above its eyes and arms even smaller than T. rex’s — the forearms were almost gone entirely. It was built for speed: long legs, a streamlined snout, and a tail that anchored powerful running muscles. Its skin is partly known from impressions, showing rows of bumpy scales but no feathers.

More about Carnotaurus

Discovery

Named by José Bonaparte · 1984 · Chubut Province, Argentina, in rocks of the La Colonia Formation

The only known skeleton (holotype MACN-CH 894) was unearthed in 1984 by an expedition led by the Argentinian paleontologist José Bonaparte. It was the eighth expedition of a project on Jurassic and Cretaceous terrestrial vertebrates of South America, and the same trip also recovered the spiny sauropod Amargasaurus.

Latin for 'meat-eating bull', from carn- (flesh) and taurus (bull), for the bull-like horns over its eyes.

José Bonaparte. Argentinian paleontologist who led the 1984 expedition that found Carnotaurus, the same expedition that also recovered the sauropod Amargasaurus.

Could Carnotaurus actually take down giant sauropods?
Its feeding habits remain unclear. Some studies suggested it could hunt very large prey such as sauropods, while others found it preyed mainly on relatively small animals. Jaw analyses indicate it was capable of quick bites rather than strong ones, which favours capturing small prey, and its flexible lower jaw may have let it swallow small items whole.
What were the horns and muscular neck for?
The distinctive horns and muscular neck may have been used in fighting members of its own species. Separate studies propose rivals may have traded quick head blows, pushed slowly with the upper sides of their skulls, or rammed each other head-on using the horns as shock absorbers.

What we know

  • Two thick bony horns above the eyes — unique among theropods.
  • Arms so short they were almost vestigial — even shorter than T. rex.
  • Skin impressions show rows of small scales (no feathers preserved).
  • Long, deep skull with a short snout — a fast bite, but lower force than a T. rex.

What we guess

  • What the horns were for — display, head-butting rivals, or both.
  • Top running speed — long legs and tail muscle attachments suggest fast, but estimates vary.
  • Why the arms shrank so much — possibly because the bite and skull took over all prey-handling jobs.