Carnotaurus sastrei was a fast, meat-eating dinosaur that lived in South America during the Late Cretaceous Period about 72 to 69 million years ago. Its name means meat-eating bull, a reference to the pair of thick horns above its eyes. Carnotaurus matters to paleontology because its nearly complete skeleton preserves rare details about body shape, skin texture, and predator anatomy.
It shows how theropod dinosaurs could evolve very different hunting designs even within the same broad group.
Key Facts
- Scientific name: Carnotaurus sastrei.
- Geologic age: Late Cretaceous Period, about 72 to 69 million years ago.
- Body length was about 7.5 to 8 m, with a mass commonly estimated around 1.3 to 2.1 metric tons.
- Speed estimate uses speed = distance/time, but fossil-based speed is inferred from limb proportions, muscle attachment, and biomechanics.
- Carnotaurus had extremely reduced forelimbs, even shorter relative to body size than those of Tyrannosaurus rex.
- Its tail was large and muscular, helping balance the body and transmit force during running.
Vocabulary
- Theropod
- A group of mostly meat-eating dinosaurs that walked on two legs and includes Carnotaurus, Allosaurus, and modern birds.
- Abelisaurid
- A family of theropod dinosaurs known for short deep skulls, small arms, and powerful hind limbs, common in southern continents during the Cretaceous.
- Fossil
- The preserved remains, impressions, or traces of an organism from the past, usually found in rock.
- Biomechanics
- The study of how living or extinct bodies move and handle forces using anatomy, physics, and engineering principles.
- Cretaceous Period
- The final period of the dinosaur era, lasting from about 145 to 66 million years ago.
Common Mistakes to Avoid
- Assuming the horns were exactly like modern bull horns is wrong because Carnotaurus horns were bony skull structures with uncertain soft tissue covering and function.
- Drawing Carnotaurus with useful grasping arms is wrong because its forelimbs were extremely small and had limited reach compared with its body size.
- Treating one fossil specimen as proof of every detail for the whole species is wrong because individuals can vary by age, sex, injury, and preservation quality.
- Saying Carnotaurus lived with humans is wrong because it went extinct tens of millions of years before humans evolved.
Practice Questions
- 1 A Carnotaurus is estimated to be 8.0 m long. If an illustration uses a scale of 1 cm = 0.5 m, how long should the dinosaur be in the drawing?
- 2 A fossil layer containing Carnotaurus is about 70 million years old. If the Cretaceous ended 66 million years ago, how many million years before the end of the Cretaceous did this animal live?
- 3 Carnotaurus had a deep skull, horns, tiny forelimbs, strong hind legs, and a muscular tail. Explain how these features suggest a predator adapted more for running and biting than for grabbing prey with its arms.