Back when tyrannosaurs were reigning supreme over the Northern Hemisphere, a similarly ferocious predator (but with a stubbier head) was ruling in the South. Recently described in a paper published in the Journal of Vertebrate Paleontology, Llukalkan aliocranianus was a key meat-eating predator munching its way through the Late Cretaceous. As long as an elephant with an impressive bite force and teeth and claws for days, its impressive characteristics – which differ from closely-related specimens – demonstrate that we have much left to learn about the diversity of a group of dinosaurs known as the abelisaurids.
The description is based on fossilized remains of L. aliocranianus which include a superbly preserved (and, crucially, uncrushed) braincase which revealed new insights into how this dinosaur assessed its environment. Holes in its skull through which its blood vessels would have passed were larger in this species compared to skulls of other abelisaurids. Its middle ear also differed, with a small posterior air-filled sinus at its center.
The researchers on the study believe this to mean that L. aliocranianus had better hearing than its relatives, with capabilities similar to that of current-day crocodiles. If correct, it's thought these new-and-improved adaptations show that abelisaurids were in their prime when they went extinct, wiped out at a time when they were still trying their hand at different evolutionary pathways giving rise to a diverse range of features among abelisaurid dinosaurs. Bummer.
While its head may be stubby, the researchers think it may have sported some snazzy accessories with bulges similar to that of Gila monsters or some iguanas. Its full name is actually derived from the native Mapuche for “one who causes fear” and the Latin for “different skull” – Llukalkan aliocranianus respectively. With its impressive size and enhanced hearing, it’s likely L. aliocranianus was among the top predators lurching around what’s now known as Patagonia (back when it was still part of the subcontinent, Gondwana). It also shared its digs with the abelisaurid Viavenator exxoni whose remains have been found near the site where L. aliocranianus was found in La Invernada, Argentina.
“This is a particularly important discovery because it suggests that the diversity and abundance of abelisaurids were remarkable, not only across Patagonia, but also in more local areas during the dinosaurs’ twilight period”, said lead author Dr Federico Gianechini, a paleontologist at the National University of San Luis, Argentina, in a statement. “This discovery also suggests that there are likely more abelisaurid out there that we just haven’t found yet, so we will be looking for other new species and a better understanding of the relationship among furilesaurs.”