In the family of Abelisauridae we can find large carnivores that travelled the planet during the Middle Jurassic, such as the Eoabelisaurus, although they were more common during the Cretaceous.
It is in the Cretaceous where we find the Majungasaurus of Madagascar that survived until the end of the Mesozoic Era, or the most famous abelisaurid, known for its large horns and small extremities, one of the most famous Argentinean theropods: the Carnotaurus.
The name Carnotaurus comes from Latin and means “flesh-eating bull”.
Do you want to discover more about this disturbing dinosaur? Then be sure to read this article where we show you a wide and detailed information about the Carnotaurus.
Taxonomy of the Carnotaurus
- The kingdom of Carnotaurus is Animalia.
- The phylum where it was classified is Chordata.
- The class to which it belonged is Sauropsida.
- Being a dinosaur, its superorder is Dinosauria.
- It was classified in the order Saurischia.
- The suborder of Carnotaurus is Theropoda.
- The family in which it was classified is Abelisauridae.
- The subfamily of Carnotaurus is Carnotaurinae.
- It was classified within the Carnotaurini tribe.
- The genus we are talking about is Carnotaurus.
The only species representing the genus, called Carnotaurus sastrei, is found in the group of theropod saurischian dinosaurs of the family Abelisauridae, an extinct genus that has left no descendants in the modern era.
The species C.sastrei has almost a complete skeleton, and also printed remains of its skin, which has facilitated its representation.
We must stress here that the fact that the only representative species of the genus Carnotaurus is C. sastrei is not necessarily definitive, since this classification may change at any time if new fossil remains belonging to the same genus but representing another species are found.
Therefore, from this platform we will do our best to keep this information updated.
Morphology and anatomy of this dinosaur
It was discovered in 1985 by the important South American paleontologist José F. Bonaparte, in Patagonia (Argentina), who also found other remains of Abelisaurids such as the Abelisaurus comahuensis (which gives its name to the family), a contemporary of C.sastrei but without horns.
The Carnotaurus was a theropod approximately 3 meters high and 8 meters long that traveled the Earth approximately 90 million years ago, during the Cretaceous, in present day Argentina, which at that time was in the super-continent of the Southern Hemisphere of the planet (Gondwana).
Its structure is common to many members of the family Abelisauridae, of which we can highlight very short front extremities, a narrow and straight skull, and as an almost unique characteristic that it only shares with the Majungasaurus, the horns of the head.
The small forelimbs were even smaller than those of the Tyrannosaurus. They are the smallest limbs in the animal world, in relation to the total body size of the animal that possesses them.
These small extremities had 4 claws in each, of which only 2 had phalanges, so these extremities were practically useless in combat, either for hunting or for defense.
The characteristic of 4 claws in the extremities is a primitive feature within the group of the theropods, since at the end of the Cretaceous the theropods possessed in their great majority only 3 claws, many of them modified to form a primitive wing.
That the Carnotaurus had 4 claws in such a short extremity indicates that in its moment it was a necessary character that was maintained by its necessity, it could use its claw as a method to maintain quiet to its preys during the hunt.
However, since the limb was atrophying due to its little use, the 4 claws were maintained because they did not exert any negative effect (in nature, if it does not exert any positive or negative effect it is often maintained or it degenerates little by little, something similar to the appendix in humans).
Its skull is very similar to other specimens of the family Abelisauridae, but it is a very special skull. It is a narrow and short skull, with wide pre- and post-orbital openings, being the largest pre- and post-orbital pits in relation to the size of the skull of any known Abelisaurid to date.
The eyes of the skull must also be detailed. Like many current predators, the eyes of the Carnotaurus were positioned so that it could have stereoscopic binocular vision, being able to calculate distances with its prey.
This is a striking feature, since the position in which they are placed gives it a very effective overlap of images between both eyes, which allowed it to calculate very accurate distances.
Another characteristic of the skull is that it is not totally solid, but was made up of different bones, allowing slight movement between them, which is called “kinetic skull”.
This type of skull allowed, during the bite, the bones that formed it to move a little bit between them, minimizing the stress that fell on the whole skull and therefore minimizing the long term damage it would suffer.
Although it also appears in other dinosaurs, the kinetic skull of the Carnotaurus is special, being the one with the largest number of small bones to minimize damage.
One of the most striking features of the Carnotaurus, and which gives it its name, are the protuberances it has in the skull, which have commonly been called horns.
Although many have in mind, at this point, that they could be used for fighting between males in a similar way to what goats or buffalo do, they could not actually charge with them as such.
Their muscular neck could help protect their spine during the charge, but their skull could not withstand more than two or three charges in a row against the skull of another Carnotaurus or other more robust skull, as buffaloes do.
It is thought that these horns, like many striking characters present in animals, served for sexual attraction in the mating season.
Another feature that does not bring much attention at first sight is the hind legs. They are very long legs, more than 2 meters long, which allowed them to take long strides. They were very muscular and fibrous legs, not very thick, allowing the Carnotaurus to be a fast predator.
A series of findings have been made, such as those of an almost complete skeleton and recent studies that have confirmed the existence of a tendon that went from the animal’s thigh to its tail, allowing a strong base that gave it a great stride power, reaching more than 45-50km/h.
The Carnotaurus was therefore a fast theropod, it could not make sharp turns but it could reach a great starting speed, without the need of a previous “warming up” time like other theropods.
Carnotaurus skin print
Among the remains found of the Carnotaurus, there is an impression of fossilized skin from the Cretaceous period. This impression informs us about the appearance of the Carnotaurus, and indicates that it was covered by osteoderms, bony plates not directly related to the bone but to the scale.
In the skin impression what has not appeared are feathers, a typical character of the contemporary theropods of the late Mesozoic.
The presence of the osteoderms allows us to differentiate two groups of these in the body of the Carnotaurus: a main group that covered the whole body in a similar way to the current Gila Monsters, and another larger and more prominent group that covered the dorsal part of the animal, from the neck to the tip of the tail.
The body of the Carnotaurus was a light bone armor that allowed it to run at high speeds but without losing the great defense that these scales gave it.
Although the skin impressions have been preserved, the colors have not been preserved, as they are lost during fossilization.
Functions of the Pre- and Post-Orbital Pits
As indicated above, the Carnotaurus has very large pre- and post-orbital pits, which has given rise to many hypotheses as to its functions.
The post-orbital fossa is located behind the eye, and it is where the jaw bones are anchored, allowing a greater or lesser power in the animal’s bite.
There are 2 hypotheses as to the power of the Carnotaurus’ bite due to this large post-orbital fossa.
The first hypothesis is that of the fatal bite. A powerful bite due to some muscles that were held in the post-orbital opening, which gave a fierce character to the Carnotaurus. The teeth, together with the power of the bite, could break even the bones.
The second hypothesis is that of the supported bite. The muscles that supported the jaw were not for a powerful bite, but for it to open and close very quickly, and wide and relatively blunt fangs, which allowed it to hold on to the prey or leave a rather ugly wound.
It is believed that along with this speed of opening and closing of the jaw, there was also the power of the neck, very muscular, which allowed efficient, fast movements and even gave strength for a possible attack (but not with the horns), preventing damage to the spine of the Carnotaurus.
The pre-orbital fossa is located in front of the eye, and it is believed that it could be full of blood vessels that allowed a change in the color of the Carnotaurus’ head, both for sexual attraction by the horns and for intimidation of an opponent.
Next to this large pre-orbital pit, regardless of whether it was watered by a large number of blood vessels, it is believed that it could have had a large number of olfactory lobes, so that the olfactory capacity of the Carnotaurus was incredible, recognizing prey or carrion from miles away.
The feeding of this dinosaur
All the characteristics we have indicated above such as short forelimbs, “weak” skull but wide jaw opening and high speed suggest that Carnotaurus attacked smaller prey than it did.
Some hunting strategies that have been suggested are that, being smaller prey, it could ram them with the skull. As they were smaller, if it was rammed from the side, the skull of the Carnotaurus could resist one or two blows, no more, which would leave the prey a little disoriented, allowing it to bite.
Even if the bite was not fatal, it could leave the prey bleeding to death, or it could even happen that by charging the prey at high speed it could cause internal damage that, in a short time, would result in death (due to internal bleeding or a perforated lung).
Because it does not possess hunting qualities such as a powerful bite (since the theory of the powerful bite described above is not widely accepted) or curved claws that penetrate the flesh, some have assumed that Carnotaurus may have been an occasional scavenger, similar to Tyrannosaurus.
This theory has lost force due to morphological characteristics that make it more similar to carnivores than scavengers.
Signs of possible cannibalism have been found in species close to Carnotaurus such as Majungasaurus.
Remains of bones were found with teeth marks in which the teeth of specimens of the same species fit, so it is not ruled out that Carnotaurus was cannibalistic on some occasions, although no remains of the species have yet been found to confirm this.
Since not many remains have been found, it is not known whether the Carnotaurus was a group, pair or single hunter.
As only one specimen has been found, it is thought that it was a solitary hunter, only grouping together or approaching another when it was breeding time or entering the territory of another Carnotaurus.
Some authors indicate that the Carnotaurus may have formed small groups to attack larger prey such as sauropods, and may have given some head butts to knock them down and prevent their escape.
As it can only be hypothesized about its socialization with other Carnotaurus, it is not known if the female, once fertilized, was abandoned by the male or continued with her to protect her offspring.
Nor is it known whether, once the young were on their feet, they were cared for by the mother (or the parents if the male stayed with the female) until they could hunt for themselves.
You can learn more about all the names of carnivorous dinosaurs in this article.