Carnotaurus was an oddity among dinosaurs, with strange horns and tiny forelimbs that made even T. rex's look useful. However, its discovery came with something that could shed light on many other carnivorous dinosaurs – fossilized skin. It's taken a surprisingly long time for this skin to get the analysis such an unusual find deserves, but now it has finally happened.
In 1984 a remarkable skeleton was discovered in Chubut Province, Patagonia. The new species of therapod was named Carnotaurus sastrei, (Sastre's meat-eating bull after the farm's owner) representing a genus with some distinctive features. However, the most remarkable part of the specimen was easily the best-preserved therapod skin ever found.
Surprisingly, studies of this skin have been very incomplete. Dr Christophe Hendrickx of Unidad Ejecutora Lillo and Dr Phil Bell of the University of New England (Australia) have rectified this in Cretaceous Research.
“By looking at the skin from the shoulders, belly and tail regions, we discovered that the skin of this dinosaur was more diverse than previously thought, consisting of large and randomly distributed conical studs surrounded by a network of small elongated, diamond-shaped or subcircular scales,” Hendrickx said in a statement.
“Contrary to previous interpretations, the feature scales are randomly distributed and neither form discrete rows nor show progressive variations in their size along parts of the body,” the authors add.
Bell noted the similarity to Australia's thorny devil, but the evolutionary benefits may not be the same.
At 8 meters (26 feet) long and possibly the largest carnivore in its environment, Carnotaurus probably didn't need the scales to protect against predators, although battles with its own kind are a different matter. The distinctive horn is thought to have been used in mating battles.
However, the authors think the skin “May have played a vital role in thermoregulation,” given how hard creatures this big find shedding excess heat, rather than being purely protective.
Previous research has shown Carnotaurus was an exceptionally fast runner thanks to tendons that attached its caudofemoralis muscle, used for flexing the tail, to its legs. This would have given it extra acceleration power, at the expense of hindering its capacity to turn. Carnotaurus made full use of this, developing the largest caudofemoralis muscle of any animal ever identified.
Thirty-seven years later, no other Carnotaurus fossil has been found, so it is just as well this one is so superbly preserved.