Carnotaurus

Lore & Background

Carnotaurus was a lightly built, bipedal predator, measuring 7.5 to 8 m in length and weighing 1.3–2.1 MT. As a theropod, Carnotaurus was highly specialized and distinctive. It had two thick horns above the eyes, a unique feature unseen in all other carnivorous dinosaurs, and a very deep skull sitting on a muscular neck. Carnotaurus was further characterized by small, vestigial forelimbs and long, slender hind limbs. The skeleton is preserved with extensive skin impressions, showing a mosaic of small, non-overlapping scales approximately 5 mm in diameter. The mosaic was interrupted by large bumps that lined the sides of the animal, and there are no hints of feathers. The distinctive horns and the muscular neck may have been used in fighting others of its species. According to separate studies, rivaling individuals may have combated each other with quick head blows, by slow pushes with the upper sides of their skulls, or by ramming each other head-on, using their horns as shock absorbers. The feeding habits of Carnotaurus remain unclear: some studies suggested the animal was able to hunt down very large prey such as sauropods, while other studies found it preyed mainly on relatively small animals.

Reader's Guide

The only skeleton (holotype MACN-CH 894) was unearthed in 1984 by an expedition led by Argentinian paleontologist José Bonaparte. This expedition also recovered the peculiar spiny sauropod Amargasaurus. It was the eighth expedition within the project named 'Jurassic and Cretaceous Terrestrial Vertebrates of South America', which started in 1976 and was sponsored by the National Geographic Society. The skeleton is well-preserved and partially articulated, with only the posterior two thirds of the tail, much of the lower leg, and the hind feet being destroyed by weathering. The skeleton belonged to an adult individual, as indicated by the fused sutures in the skull. It was found lying on its right side, showing a typical death pose with the neck bent back over the torso. Unusually, it is preserved with extensive skin impressions. In view of the significance of these impressions, a second expedition was started to reinvestigate the original excavation site, leading to the recovery of several additional skin patches. The skull was deformed during fossilization, with the snout bones of the left side displaced forwards relative to the right side, the nasal bones pushed upwards, and the lacrimal pushed backwards onto the frontal. Deformation also exaggerated the upward curvature of the upper jaw. The snout was more strongly affected by deformation than the rear part of the skull, possibly due to the higher rigidity of the latter. In top or bottom view, the upper jaws were less U-shaped than the lower jaws, resulting in an apparent mismatch. This mismatch is the result of deformation acting from the sides, which affected the upper jaws but not the lower jaws, possibly due to the greater flexibility of the joints within the latter. The skeleton was collected on a farm named 'Pocho Sastre' near Bajada Moreno in the Telsen Department of Chubut Province, Argentina. Because it was embedded in a large hematite concretion, a very hard kind of rock, preparation was complicated and progressed slowly. In 1985, Bonaparte published a note presenting Carnotaurus sastrei as a new genus and species and briefly describing the skull and lower jaw. The generic name Carnotaurus is derived from the Latin carno [carnis] ('flesh') and taurus ('bull') and can be translated with 'meat-eating bull', an allusion to the animal's bull-like horns. The specific name sastrei honors Angel Sastre,

Did You Know?

• Carnotaurus means 'meat-eating bull', referring to its bull-like horns.
• The only known skeleton was found in 1984 in Chubut Province, Argentina, by an expedition led by José Bonaparte.
• Carnotaurus had two thick horns above its eyes, a feature unique among carnivorous dinosaurs.
• The skeleton preserves extensive skin impressions showing small scales and large bumps, with no hints of feathers.
• Carnotaurus was one of the largest abelisaurids, measuring 7.5–8 m in length.

Common Misconceptions (Editorial)

Some believe Carnotaurus was a horned dinosaur like a triceratops, but its two thick horns were above the eyes, not on the nose or brow ridge in the same manner. Another misconception is that its skull shape in reconstructions is fully accurate; in reality, the skull was deformed during fossilization, exaggerating the upward curvature of the upper jaw. It is also sometimes thought to be poorly known, but Carnotaurus is actually one of the best-understood theropods from the Southern Hemisphere, known from a single well-preserved skeleton with extensive skin impressions.

Why It Matters (Editorial)

Carnotaurus endures in the public imagination because it looks like no other dinosaur — a theropod with bull-like horns that still feels alien and predatory. Its exceptional preservation, including skin impressions that have guided accurate life restorations, makes it a vital window into the appearance and biology of abelisaurids, the top predators of ancient South America.