The community of savage thieves in the age of dinosaurs has now gained another member: the attending paleontologists Llukalkan aliocranianus – “Terrifying with the other skull.” The predatory dinosaur, which reached about five meters in length, belonged to the group of Abilisaur, which was common in the southern Cretaceous world. In addition to other special skull features, Llukalkan distinguished unusual structures in the hearing organ. Accordingly, he may have had a particularly keen hearing, which distinguished him from his relatives who were at the same time in his living space, according to the scientists.
In the late Cretaceous period, the world of predatory dinosaurs was divided into two domains: in the greater northern continent of Laurasia, representatives of tyrannosaurs in particular evolved into the highest predators. In southern Gondwana, however, Abilisour assumed the role. Fossil discoveries show that different species of these legged dinosaurs roamed what is now Africa, India, Antarctica, Australia and South America. Although their growth lines split early, southern predators resembled their northern “mates” in many ways: Applesores were five to nine meters long, had clawed hind legs, small short arms and terrifying teeth. Unlike T. rex and Co, they had rather short skulls, some of which featured combs and horns or at least with prominent sinuous structures.
New representative of “southern predatory dinosaurs”
According to the paleontologists’ report on Federico Gianechini of San Luis National University, the new representative of Apilisaurus also had a corresponding “knobbly” appearance. Its remains were discovered in the Pago de la Carba Formation in western Argentina and date back about 80 million years. The fossil consists of a skull preserved almost entirely with sharp teeth. Based on comparisons of size with other fossils known to representatives of the plesiosaurs, the researchers concluded that the animal, presumably not yet fully developed, was about five meters long. Like these, the predatory dinosaur also probably wore huge claws on its powerful feet, which could stab its prey, as it were.
This applesor was large, fast, and hugely armed – making it one of the best predators in its habitat, scientists say. They gave him the scientific name Llukalkan aliocranianus. It is made up of the original Mapuche word meaning “terrifying” and the Latin word for “another skull” – Aleukranianus. The title indicates the detailed results of the fossil investigations. Accordingly, the Lukalkan had a particularly short skull with special bulges and protrusions. As a result, its head resembled the head of some of today’s iguanas, paleontologists say.
An indication of acute hearing
However, according to them, the most striking feature of the skull in the new dinosaur is an unusual area in the middle ear region that has not been observed in any other Applesor animal found so far. “This result indicates a special auditory modification compared to other abilisaurs.” “Maybe Lukalkan had a keen sense of hearing,” says co-author Ariel Mendes of the Patagonia Institute of Geology and Paleontology in Puerto Madryn.
As scientists explain, this discovery sheds light on the evolution of species diversity among predatory dinosaurs at the end of the Cretaceous period. Because Llukalkan apparently shared its habitat with at least another relative: the remains of Abelisaur Viavenator exxoni were discovered only 700 meters from its pits. “This is important because it indicates that the diversity in these predatory dinosaurs was not only great in general, but at the local level as well,” says Giancini. Apparently, different adaptations – such as hearing skills – enabled large different species of predatory dinosaurs to coexist.
It remains unclear how Llukalkan lived, who stalked him and what advantages his own auditory abilities might have conveyed to him, but the fossil finding document revealed adaptations, the researchers say. “These dinosaurs were still trying new evolutionary paths and diversifying rapidly before disappearing in the great mass extinction at the end of the Cretaceous period,” Mendes says. In this context, they now hope to find more discoveries: “The new discovery indicates that more representatives of the Pliocene are waiting for their discovery. In any case, we will now look for more ways to gain more insight into their relationships with each other,” says Jianchini.
Source: Taylor & Francis Group, Special Article: Journal of Vertebrate Paleontology, doi: 10.1080 / 02724634.2020.1877151