Carnotaurus

The Origin of “Meat-Eating Bull” and the Mystery of Its Horns

The scientific name Carnotaurus means “meat-eating bull” in Latin.
As the name suggests, their most distinctive feature is their head.
With a face reminiscent of a bulldog—tall vertically and compressed horizontally—it possessed two thick horns protruding sideways above its eyes.
Its appearance is truly that of a “bull in the shape of a lizard.”

It had two thick horns protruding sideways above its eyes.

It is extremely rare for carnivorous dinosaurs to have such horns, and their purpose has long been a mystery.
Since they lacked the strength to be used as weapons, the prevailing theory today is that they functioned as “intra-specific display.”
It is believed that the size of the horns was used as an appeal point to attract females or to intimidate rival males.

The “Ultimate Tiny Arms”: More Vestigial Than Tyrannosaurus

Essential to discussing Carnotaurus are its extremely vestigial forelimbs.
While Tyrannosaurus is famous for its small arms, Carnotaurus takes this to the extreme, with arms measuring only about 50 cm long.

Its forelimbs were only about 50 cm long.

The elbow and wrist joints were fused, making it look at first glance as if the hand grew directly from the upper arm.

However, they were not simply degenerate.
While many advanced theropods reduced their digit count, Carnotaurus retained a primitive “four fingers.”
Even more surprisingly, despite the arms being minuscule, the shoulder girdle was well-developed, revealing that the range of motion in the shoulder was remarkably wide.
The purpose of these bizarre forelimbs remains even more shrouded in mystery than the horns.

The Fastest Giant Hunter on Land? Astonishing Physical Abilities and the “Caudofemoralis”

Contrary to its strange appearance, recent research has revealed that Carnotaurus was likely a hunter possessing terrifying physical capabilities.

According to a 2011 study, Carnotaurus is considered one of the “fastest dinosaurs,” boasting top-class speed among all large theropods.
The basis for this is the size of the “caudofemoralis,” a muscle extending from the tail to the thigh.
Research suggests that the caudofemoralis of Carnotaurus was among the largest of any animal on Earth.

Its caudofemoralis muscle was among the largest of any animal on Earth.

It is believed that this robust muscle generated explosive propulsion, allowing for tremendous charging power like a bull.
However, in exchange for this massive muscle, the tail had low flexibility, and it is presumed that it could not turn very tightly.
It may have specialized in a style of closing the distance instantly with overwhelming straight-line speed to deliver a powerful strike.

It boasted top-class speed among large theropods.

Proof of “Scales” in the Age of Feathers

In recent years, the theory that “carnivorous dinosaurs had feathers” has become common, but regarding Carnotaurus, it is asserted that it “almost certainly did not have feathers.”

This is due to the exceptionally good condition in which the Carnotaurus fossil was discovered.
Fossils discovered in Patagonia in 1985 preserved clear impressions (traces) of “scaly skin.”
This confirmed that Carnotaurus had reptile-like scale-covered skin, making it an extremely important resource in the study of the Abelisauridae family.

One of the Largest Species of Abelisauridae

Carnotaurus is estimated to have been approximately 7.5 to 9 meters long and weighed 1.35 to 2.1 tons.
It was once considered the largest among abelisaurids, but in recent years, a species called Pycnonemosaurus has emerged as a rival.
Regardless, Carnotaurus undoubtedly possessed a massive body representing this group.

Thanks to the well-preserved complete skeleton and even skin traces, Carnotaurus is particularly well-studied among the Abelisauridae.
Its unique appearance and abilities tell the story of how diverse dinosaur evolution was, exceeding our imagination.