This fellow — or at least his robust skull with the short, knobby eyebrow horns and fierce-looking teeth — is on display at the Natural History Museum in Madrid, Spain. For now, he is the only known genus of this species of bipedal predator.
The first specimen of Carnotaurus sastrei was found in Chubut on vast plains between the Andes Mountains and the Atlantic Ocean. A physician, Dr. A'ngel Tailor noticed a large concretion showing some bone fragments. A team led by José F. Bonaparte excavated the find in 1984 as part of a paleontological expedition funded by the Argentine Museum of Natural Sciences.
Sadly, Bonaparte — the Maestro del Mesozoico — passed away the 18th February of this year at the age of 91. He spent the majority of his career as head of the Vertebrate Palaeontology Division of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia,” in Buenos Aires. Bonaparte opened up the vertebrate finds of Argentina to the world. He was instrumental in the finding, excavating and naming many iconic dinosaurs — Carnotaurus, Amargasaurus, Abelisaurus, Argentinosaurus, Noasaurus along with the finding of the first fossilised remains of Mesozoic South American mammals. He mentored many palaeontologists who will miss his keen eye and tremendous work ethic — Luis Chiappe, Rodolfo Coria, Agustín Martinelli, Fernando Novas, Jaime Powell, Guillermo Rougier, Leonardo Salgado, Sebastián Apesteguía and many others.
His excavation of Carnotaurus was the first of its kind and he recognized that the skull is quite unusual. Initially, it has a very marine reptile feel — but make no mistake this guy is clearly a terrestrial theropod. He had smallish, underdeveloped arms — teeny by theropod standards. Once you look closer you see his bull-like horns from whence he gets his name — horns that imply battle between rivals for the best meal, sexual partner and to be the one who leads the herd.
He was covered in leathery skin lined with rows of cone-shaped nodules or bumps. These get larger as they move towards his spine. He had forward-facing eyes, similar to tyrannosaurs like T-rex and smaller theropods like Velociraptor and Troodon — who had better vision even that T-rex — which would have given him the advantage of binocular vision and depth perception. Forward-facing eyes are also quite helpful with nocturnal hunting — think owls and cats — as they take in more light and help with nighttime predation. So perhaps this flesh-eating bull fancied a late-night snack on his menu from time to time.
Species like squirrels, pigeons and crocodiles have eyes on the sides of their heads. They lack the important competitive feature of well-developed depth perception — being able to easily and estimate distance — but perhaps make up for it with a panorama that offers a wider field of view.