Carnotaurus

## CarnotaurusMeat Bull

* Male
* Female

* **Horn (bone core) Length** of 15 centimeters (6 inches)
* **Bite Force** of 750 - 800 pounds
* **Top Speed** of 48 - 56 kilometers (30 - 35 miles) per hour

***Carnotaurus*** (Meat Bull) is a genus of abelisaurid theropod dinosaur that lived in the La Colonia Formation, Chubut Province, Argentina, 71 - 69 million years ago, during the Maastrichtian stage of the Late Cretaceous Period.

## Paleobiology

### Size and Physique

*Carnotaurus* is one of the longest abelisaurids, at around 7.5 - 8 meters (24 - 26 feet) long, with only *Pycnonemosaurus* of Brazil being longer at around 9 meters (30 feet). The theropod has been estimated to weigh anywhere from 1.3 metric tons (1.5 short tons) to 2.1 metric tons (2.3 short tons). Despite being one of the largest abelisaurs, it is believed to be lightly-built, hence why it is one of the fastest large theropods, able to run at a maximum of 48 - 56 kilometers (30 - 35 miles) per hour. The male in the show is stated to be two metric tons (2.2 short tons) in weight, and 12 feet (3.66 meters) in height, with the female said to be bigger and stronger, which also reflects how, while male animals tend to be more vibrant in terms of display, female animals tend to be larger and deadlier than their male counterparts (though it's also possible that the male just so happened to call the attention of a female older than him). As with all abelisaurs, *Carnotaurus* is believed to have a bite force similar to that of *Allosaurus*, around 750 - 800 pounds.

### Rugged Features

Being an abelisaur, it had rough skin, made even more rugged by feature scales randomly scattered and distributed all over the body, as well as short arms that appear vestigial, with no wrist bones and immobile elbow joints. Prehistoric Planet instead depicts these arms as useful tools in mating displays. One argument regarding *Carnotaurus* using its tiny arms for this purpose is the lack of sufficient nerve supply in these limbs, much like the wings of emus and kiwis. Dr. Darren Naish, Prehistoric Planet's lead consultant, counters this by bringing up how such an argument ignores cassowaries, which possess long spikes on their forearms, indicating some sort of function.

Atop its skull, which is tall, short in terms of length, and robust like other abelisaurs, is the pair of eyebrow horns that give the animal its name, with studies still arguing over whether these horns were merely for display, used for slowly pushing against rivals, utilized for more active, high-speed ramming and swinging, or even serve as the only case in the animal kingdom of horns being used as tools for predation. Regardless, it is believed that these horns were just bone cores covered by keratinous sheaths that make them longer than they first appear to be (though some argue that, should they exist, such keratinous sheaths would not have significantly lengthened the horns).

### Sounds

***“ All is ready, and he announces the fact. His calls are low-pitched, and travel much farther through the dense vegetation than higher-pitched ones would do. ”***

― **David Attenborough**, *Forests*
On Prehistoric Planet, the male *Carnotaurus* is depicted calling out to potential mates with deep rumbling growls and booming bellows that resemble the drumming of an emu rather than the stereotypical roar often associated with dinosaurs. As with birds, crocodiles, and other reptiles, *Carnotaurus* does not need to open its mouth in order to vocalize, as vibrating and amplifying the sound of air within the body is sufficient. Its relatives, *Majungasaurus* and *Rajasaurus*, would also be depicted making similar guttural sounds.

### Prehistoric Planet's Depiction

***“ He doesn't have huge antlers, nor a spectacular tail, though he does have a pair of tiny, apparently useless arms. And each has a ball-and-socket joint at its base that enables him to move them independently. ”***

― **David Attenborough**, *Forests*
***Carnotaurus*** is erroneously depicted with its scales arranged in a neat pattern all over its body. A study of skin impressions in 2021 showed that, in truth, *Carnotaurus*, like all abelisaurs, had its scales randomly distributed across their body. This mistake was corrected for *Majungasaurus* and *Rajasaurus*, which were depicted in Season 2 of Prehistoric Planet with a more random arrangement of scales on their bodies.

Prehistoric Planet features only one male and female *Carnotaurus*, but this is enough to showcase the sexual dimorphism between them. As with many animals, since it is the male that needs to impress the female, the male *Carnotaurus* has a more striking orange coloration in contrast with the female, which is mostly dark gray color with flesh-pink shades. Both have a brown back with brown stripes covering the rest of the body, though this stands out more on the male's orange skin. Even though they have prominent eye horns that can properly serve as display, the male *Carnotaurus* also has the undersides of his arms colored vibrant blue. On the show, the presence of ball-and-socket joints for the arms of *Carnotaurus* is used as justification for their use in some sort of purpose, in this case, mating displays.

## Paleoecology

### Paleoenvironment

***“ In Patagonia, the thick vegetation stretches unbroken for hundreds of miles. But occasionally, there are mysterious clearings, like this one. It's the work of a two-tonne, 12 foot-tall Carnotaurus, a male. ”***

― **David Attenborough**, *Forests*
*Carnotaurus* lived 71 - 69 million years ago in the La Colonia Formation, which is situated in the Chubut Province of Argentina, South America. It is believed that part of the area represents a watery environment close to the coast. Dr. Darren Naish, the lead consultant of Prehistoric Planet, brought up how, although *Carnotaurus* is usually associated with badland-esque environments in popular culture, in actuality, the place it has been found in had the sediments and plant life that serve as evidence of freshwater and vegetation, and the implied climate of the area indicated that *Carnotaurus* lived in an area within (or at least close to) deciduous and evergreen forest environments. Layers of clay, shale, and sandstone indicate that at least part of the region was close to the shoreline.

### Mating Habits

***“ At last, a female arrives. She's bigger than the male, and more powerful. Now, somehow, he must impress her... and he may only get this one chance. ”***

― **David Attenborough**, *Forests*
Prehistoric Planet depicts the male *Carnotaurus* engaging in a lively mating dance to attract females, a behavior reminiscent of some modern birds. In preparation for this display, the male *Carnotaurus* first clears out a patch of the forest that is more exposed to sunlight. This clearing could serve to emphasize his territory and potentially enhance his appeal to potential mates.

Similar to many animal species, female *Carnotaurus* are depicted as being selective and hard to impress. They likely consider various factors such as strength, age, and the vigor displayed during the mating dance, factors that the next generation needs to ensure further success of his lineage. Every bit of effort the male exerts can enhance or degrade how attractive he may seem, suggest how well he (and by extension, his kin) can secure prey and territory, or even somehow show that he has good fatherhood skills (assuming that male *Carnotauruses* are involved in raising their young).

## Appearances

### Forests

In the third segment of the episode, a male *Carnotaurus* is seen cleaning up a patch of the forest under an area of the forest that is more open. His purpose is to serve as a stage on which he can attract females. After tidying up the area, he lets out a low-pitched, rumbling growl through the forest. He ends up attracting a female bigger and more powerful than he is. Starting out with a slow dance, bowing, waving his tail, turning around, and swaying, he rears up, flicks out his arms, and begins dancing more energetically, doing the same moves at a faster pace while twirling his arms, highly mobile due to the ball-and-socket joints by the shoulders. The male finishes his dance and rears up, his arms extended to their fullest extent. The female sniffs him, and, unfortunately, decides he is unworthy for some unknown reason, and walks away.

***“ Not today. How could he have done better? Who knows? For now, it's back to litter-picking. ”***

― **David Attenborough**, *Forests*
Dejected, the male returns to tidying up his small patch of land in the forest in preparation for his next, hopefully more successful attempt.

### Prehistoric Planet: Uncovered - Armed for Seduction?

  **Armed for Seduction?**
**Subject**
The small arms of theropod dinosaurs, as well as their purpose as courtship displays.

**Experts**
Dr. Darren Naish, Professor John Hutchinson
***“ Everyone knows that T. rex had small arms. But dozens of predatory dinosaurs from all around the world had small arms too. They all evolved from earlier dinosaurs that had much longer arms, but over millions of years, these dinosaurs came to rely more on their mouths for holding and killing prey, so their heads became more powerful, and their arms became smaller. ”***

― **Dr. Darren Naish**, *Lead Scientific Consultant*
Footage from the Forests *Carnotaurus* segment is used for this Uncovered segment, which is focused on the discussing the small arms of some dinosaurs. *Carnotaurus*, along with other abelisaurs, had the smallest arms in proportion to their body size, even shorter than those of tyrannosaurs, with no defined elbows, wrists, or even claws on their fingers. Hence, these arms appeared to be nothing more but leftovers much like a human's tailbone, useless and vestigial.

But given its ball-and-socket joint by the humerus (upper arm bone), right where it meets the shoulder, held by many powerful muscles, it appears that, contrary to being worth nothing, the arms were highly mobile, implying that they had a purpose of some sort. The most likely use they had was for display.

***“ In the natural world today, highly-specialized body parts that appear to have no other function also turn out to be used for display and to attract mates. These range from colorful feather plumes to long, cumbersome horns and antlers. In many cases, the owner of such appendages puts up with the cost of having them because they are so attractive to potential mates. In modern-day birds and reptiles, iridescent colors also help visible displays to stand out, and the same could be true for Carnotaurus's arms. ”***

― **David Attenborough**, *Prehistoric Planet: Uncovered - Armed for Seduction?*
The justification is that brightly-colored appendages combined with a wide range of motion is definitely eye-catching, though of course, despite all attempts and efforts in putting on the best display, potential mates can still prove very selective when it comes to their choices.

## Trivia

* *Carnotaurus* is the only abelisaurid on Prehistoric Planet not shown hunting.
* The third segment of Forests is the sixth one to feature a courtship ritual, and the second one where the courtship ritual failed not because of a rival male, but due to a female being unimpressed by the male's mating display.

## References

### General

1. ↑ 1.0 1.1 1.2 1.3 *The Princeton Field Guide to Dinosaurs*
2. ↑ 2.0 2.1 The skull of *Carnotaurus sastrei* Bonaparte 1985 revisited: insights from craniofacial bones, palate and lower jaw
3. ↑ 3.0 3.1 Ceratosaur palaeobiology: new insights on evolution and ecology of the southern rulers
4. ↑ 4.0 4.1 Predatory dinosaur was fearsomely fast
5. ↑ 5.0 5.1 The scaly skin of the abelisaurid *Carnotaurus sastrei* (Theropoda: Ceratosauria) from the Upper Cretaceous of Patagonia
6. ↑ 6.0 6.1 Scientists reveal the fossilized skin of a bull-like carnivorous dinosaur
7. ↑ On the Palaeobiology of the South American Horned Theropod *Carnotaurus sastrei* Bonaparte
8. ↑ Gasparini et al., 2015

### Dr. Darren Naish

1. ↑ The idea that *Carnotaurus* lacked an adequate nerve supply to play any important role is based on comparisons with the useless wings of emus and kiwis, but this argument ignores cassowaries, which have long spikes on their forelimbs that may have played an important role.
2. ↑ *Carnotaurus* is usually depicted within an arid, rocky environment, but associated plants and sediments indicate that it lived in areas with persistent freshwater and vegetation, with climate modeling showing both deciduous and evergreen forests near the location of *Carnotaurus*.