Carnotaurus

*Carnotaurus sastrei*

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***Carnotaurus*** (pronounced "KAR-nuh-TORE-us", meaning "meat-eating bull") is a genus of large theropod dinosaur that lived in South America during the Late Cretaceous period, about 68 to 66 million years ago. It could grow about 9 feet (2.7 metres) tall and 29 feet (8.8 metres) long.

The only known species to date is *C. sastrei* , which is known from a single, well-preserved set of remains, it is one of the best-understood theropods from the Southern Hemisphere. During its time, *Carnotaurus* was apart of the large predatorial niche in the southern regions of Gondwana.

Palaeontologists are uncertain to the phylogenetic relationship of *Carnotaurus*; it is believed to be close to either *Majungasaurus* or *Aucasaurus* .

## Description

*Carnotaurus* is an abelisaurid — the carnivorous dinosaurs that succeeded the carcharodontosaurids and ruled Cretaceous South American ecosystems like tyrannosaurids did in the North. Being the first of its clan to be known from relatively complete remains it did a sterling job of showcasing their weird features.

Abelisaurids' small arms, attached to massive shoulder blades, were nothing more than wrists with a couple of fused, clawless fingers. Though practically useless, studies have shown that Carnotaurus's arms exhibited an impressive range of movement, implying that they might have had a role in visual display or helped it get off the ground after resting. They also had a short and high skull, but *Carnotaurus* skull looks pretty different from other abelisaurids. It had two horns above its eyes as well.

    The eyes of *Carnotaurus* face fully forward which hints at binocular vision, and scientists recently discovered that it had the largest "caudofemoralis" muscle of any land-dwelling animal ever, relative to body size. Supported by pairs of interlocking rib-like bones along the underside of its tail and attached by a tendon to a finger-like nub of bone (fourth trochanter) on the rear of each upper leg bone (thigh), this muscle was a power pack for explosive acceleration, but it came at a cost. Unfortunately, the tail-stiffening bone structure resulted in a loss of manoeuvrability and hampered quick, fluid turns, but for straight ahead A to B hunting there was no swifter large theropod dinosaur.

An unusually slim lower jaw compared to the extremely deep skull to which it was attached raised questions about its feeding habits that so far no-one has been able to answer. But what we can be sure of, thanks to preserved skin impressions, is that *Carnotaurus* had scaly skin with osteoderms and most likely wasn't feathered.

## Discovery

The first fossils of *Carnotaurus* were discovered at "Estancia Pocho Sastre"  in the La Colonia Formation (initially thought to be from the older Gorro Frigio aka Cerro Barcino Formation), Chubut Province, Argentina, by José F. Bonaparte in 1984. The holotype (MACN-CH 894) is a skull and partial skeleton with some skin impressions.

## JPInstitute.com Description

Carnotaurus was a South American, meat-eating dinosaur that had two short horns above its eyes. The horns were probably used more to impress females than for fighting. Another unusual feature was that it had very probably the tiniest arms of any of the larger meat-eaters.

Discovered fairly recently (1985), this fossil was very complete and included the best theropod skin impressions ever found. The skin showed many small cone-shaped nodules, each about two inches (5 cm) across, regularly spaced over its body. Carnotaurus had a short snout for a larger theropod. Its skull measured only 22 inches. Its arms were so small that it almost appears that the hands sprouted right from its body.

## Dinosaur Field Guide Description

Camotaurus ("meat-eating] bull") was one of the most bizarre meat-eating dinosaurs ever found. Its skull was short. with armor on the top and a pair of knobby horns over its eyes. The neck and shoulder blades were well developed, but the arms were incredibly short, with forearms so shrunken they were practically just wrists! Not even Tyrannosaurus rex had such small arms. With its small skull, Carnotaurus might not have been able to attack big plant-eaters, but it was probably fast and could have easily chased down smaller, more agile prey. The horns of Carnotaurus look something like those of a bull--and like a bull, it may have used them in contests with others of its own species. In this way, two Carnotaurus could test each other's strength without either of them seriously injuring the other.

### Fun Facts

The first, and so far only, discovered specimen of Carnotaurus was found with impressions of skin from all over the body.

### Trivia

In Michael Crichton's novel The Lost World: Jurassic Park 11, the genetically recreated Carnotaurus had the power of chameleon-like camouflage However, it is extremely unlikely that any dinosaur really had this ability.

## Links

http://web.archive.org/web/20040413101415fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_carno.html#

## References

1. ↑ 1.0 1.1 Candeiro, Carlos Roberto dos Anjos; Martinelli, Agustín Guillermo. "Abelisauroidea and carchardontosauridae (theropoda, dinosauria) in the cretaceous of south america. Paleogeographical and geocronological implications". Uberlândia. Sociedade de Naturaleza. 17 (33): 5–19.
2. ↑ Canale, Juan I.; Scanferla, Carlos A.; Agnolin, Federico; Novas, Fernando E. (2009). "New carnivorous dinosaur from the Late Cretaceous of NW Patagonia and the evolution of abelisaurid theropods". Naturwissenschaften. 96 (3): 409–14. Bibcode:2009NW.....96..409C. PMID 19057888. doi:10.1007/s00114-008-0487-4.
3. ↑ Bonaparte, José F. (1985). "A horned Cretaceous carnosaur from Patagonia". National Geographic Research. 1 (1): 149–151.