Carnotaurus
Name:
Carnotaurus
(Meat eating bull).
Phonetic: Car-no-tore-us.
Named By: Jos� Bonaparte - 1985.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Abelisauridae, Carnotaurinae,
Carnotaurini.
Species: C. sastrei (type).
Type: Carnivore.
Size: 8 meters long.
Known locations: Argentina, Chubut Province -
La Colonia Formation.
Time period: Campanian to Maastrichtian of the
Cretaceous.
Fossil representation: One almost complete
skeleton, including skin impressions.
While
Carnotaurus had the standard theropod morphology of
a bipedal animal
with large head and small arms, it still possessed a number of
features that made it quite unique among the large theropods. One
such feature is the arms, which are not just small like you would
expect, but are positively tiny. Further to this the fingers were
fused together meaning they could not move independently from one
another. On top of this the fingers also lacked claws. Had
Carnotaurus not gone extinct, its descendents may
have
eventually lost these arms
all together.
Carnotaurus
displays a short and deep (tall) skull, something which is
characteristic of the abelisaurid
group. Despite this height depth
however, the skull was very narrow, and the mandible (lower jaw)
very small. This means that Carnotaurus did not
have the
requirements to support strong muscle attachment, and as such it
probably had quite a weak bite force, especially when compared to the
large tyrannosaurids.
A
weak bite is often taken as being indicative of an animal that is not
an active hunter, but this supposition is only valid for animals that
actually rely upon bit force alone to kill prey. Study of the
Carnotaurus skull has revealed that it could support
downward thrusting
motions against a prey creature. This has brought the suggestion that
Carnotaurus may have used its head like a club or
hatchet by dropping
its head down hard and fast while the mouth was open so that the teeth
penetrated with the momentum of the strike instead of by muscle
strength alone.
This
is particularly interesting when you consider the neck of Carnotaurus
was also quite long compared to others and would have helped to
facilitate such 'hacking' action from the skull. Also the jaws
have been found to be capable of opening very quickly, further
implying that a flurry of fast strikes may have been used to take down
prey.
Despite
the fact that it had a weaker bite force compared to other large
theropods, Carnotaurus still had a highly
specialised skull. The
skull of Carnotaurus was not a solid feature but
was actually what is
termed kinetic. This means that as Carnotaurus
ate, or took a bite
out of something, different parts of the skull would move around in
order to reduce the total stress on the bone. Even though kinetic
skulls are known in other dinosaurs, in Carnotaurus
the movable skull
are parts are even more numerous and developed giving Carnotaurus
what
it considered by some to be the most kinetic dinosaur skull known.
Another
good bit of evidence that points to Carnotaurus
being an active
predator is the placement of the eyes. In Carnotaurus
the eyes are
angled to face slightly forward enabling Carnotaurus
to see in
stereoscopic (or binocular) vision. This is a common feature of
predatory animals that allows depth perception, the ability to judge
distances between you, and in the case of Carnotaurus,
prey. Tied
into this are the legs, the long length of which indicate a
predator that could reach quite respectable speeds when chasing after
prey.
The
most often referred feature of Carnotaurus is of
course the horns
above its eyes. Although they were likely display features in a
similar manner to the horns of Ceratosaurus,
or the double crests of
Dilophosaurus,
some palaeontologists have suggested practical uses
for them as well. One proposed use is that the horns would be used
in 'butting' contests with rivals, although others are of the
opinion that the skull is too weak to withstand the stresses. This of
course doesn't discount the possibility that the horns could be used
for flank butting, perhaps explaining the reduced fore limbs.
Others have envisioned the horns as stabbing weapons for use against
prey, perhaps a compensation for a weaker bite. Regardless of any
specific purpose, it is the presence of these horns that is the
reason why Carnotaurus is enjoying an increasing
amount of exposure in
popular culture.
Another
abelisaurid known to have had a short spike on its skull is
Majungasaurus
from Madagascar.
Further reading
- Carnotaurus sastrei Bonaparte, the horned,
lightly built carnosaur
from the Middle Cretaceous of Patagonia - Jos� F. Bonaparte, Fernando
E. Novas & Rodolfo A. Coria - 1990.
- On the palaeobiology of the South American horned theropod
Carnotaurus sastrei Bonaparte - Gerardo V. Mazzetta,
Richard A. Fari�a
& Sergio F. Vizca�no - 1998.
- Dinosaur Speed Demon: The caudal musculature of Carnotaurus
sastrei
and implications for the evolution of South American abelisaurids - W.
S. Persons & P. J. Currie - 2011.
- The hand structure of Carnotaurus sastrei
(Theropoda, Abelisauridae):
implications for hand diversity and evolution in abelisaurids - Javier
Ruiz, Ang�lica Torices, Humberto Serrano & Valle L�pez - 2011.
- The braincase anatomy of Carnotaurus sastrei
(Theropoda:
Abelisauridae) from the Upper Cretaceous of Patagonia - Ariana Paulina
Carabajal - 2011.
- The skull of Carnotaurus sastrei Bonaparte 1985 revisited: insights
from craniofacial bones, palate and lower jaw. - Historical Biology. 33
(10): 2444–2485. - M. A. Cerroni, J. I. Canale & F. E. Novas -
2020.
- The scaly skin of the abelisaurid Carnotaurus sastrei
(Theropoda:
Ceratosauria) from the Upper Cretaceous of Patagonia. - Cretaceous
Research. 128: 104994 - Christophe Hendrickx & Phil R. Bell -
2021.
Random favourites
 |
 |
 |