Kileskus

Phylogeny: Dinosauria > Saurischia > Theropoda > Neotheropoda > Tetanurae > Avetheropoda > Coelurosauria > Tyrannosauroidea > Proceratosauridae

Overview: Kileskus is one of the oldest known tyrannosaurs from the fossil record, rivaled only by the genus Proceratosaurus, from what is now England. Kileskus itself lived in what is today central Russia, its fossils having been found in the region of Krasnoyarsk, in Siberia. Said fossils came from the Itat Formation, meaning Kileskus would’ve lived around one hundred and sixty-six million years ago. Both it and Proceratosaurus belonged to the family Proceratosauridae, which is generally seen as the most basal lineage within the tyrannosauroid superfamily. During the Middle Jurassic, tyrannosaurs were only minor predators, usually going after smaller prey. They themselves may’ve been preyed on by larger theropods, mainly megalosaurids or early allosaurs. Kileskus is currently the only dinosaur described from the Itat, though fossils of other dinosaurs have been found there. Described in 2010, its scientific full name, Kileskus aristotocus, translates as “lizard of noble origin”, partly derived from the local Khakas language.

Paleontologists estimate Kileskus to have been about four or so meters long, so it was a far cry from the behemoths that would later emerge from its superfamily. This was average for a member of the Proceratosauridae. Kileskus is primarily known from bits of its skull and some bones from the hands and feet. What we know about other proceratosaurids can help us to reconstruct its life appearance. These dinosaurs tended to have long arms, unlike the most derived tyrannosaurs, as well as three clawed digits. Kileskus likely had a bony crest over its snout, as we can see on both Proceratosaurus and Guanlong. We have direct fossil evidence that these early tyrannosaurs had simple proto-feathers over most of their bodies, but later tyrannosaurs may’ve lost them due to obtaining such huge sizes. The proceratosaurid Yutyrannus, from the Early Cretaceous of China, was decently large for its time and still had proto-feathers, however.