Llukalkan

Llukalkan (Mapuche for "one who causes fear") is a genus of abelisaurid theropod dinosaur from the Late Cretaceous Bajo de la Carpa Formation of Argentina. The type species is Llukalkan aliocranianus.
Discovery and naming.
The holotype of "Llukalkan", MAU-Pv-LI-581, consisting of a partial skull, was discovered in the La Invernada site in Neuquén Province, Argentina, in the rocks of the Bajo de la Carpa Formation. It was discovered only away from the remains of fellow abelisaurid "Viavenator". It was described as belonging to the new taxon "Llukalkan aliocranianus" in 2021; the generic name is Mapuche for "one who scares" or "one who causes fear", and the specific name is Latin for "different skull".
Description.
"Llukalkan" is very similar to "Viavenator", except that it is smaller, the holes in the skull through which the veins pass are larger and more widely separated from the supraoccipital crest, among other differences. It also has a small posterior air-filled sinus in the middle ear zone, a "recessus tympanicus caudalis", that has not been found in any other abelisaurids and thus is an autapomorphy.
Paleobiology.
On account of its unusual ear, it has been theorized than "Llukalkan" had a keener sense of hearing than other abelisaurids, almost like a crocodile's.
Classification.
Gianechini "et al." place "Llukalkan" as a derived abelisaurid, in the clade Furileusauria. Their cladogram is shown below.