The hind limb ontogeny of Troodon formosus

Abstract

The Campanian theropod Troodon formosus has long been recognized as one of the most exceptional dinosaurs of the Late Cretaceous. Despite its relatively small size, it was a remarkably advanced and specialized creature, with one of the largest encephalization quotients among dinosaurs, serrated teeth with hypertrophied denticles, and long hind limbs suited for agility and energy-efficient locomotion. Yet much is still unknown about members of this species due to the fragmentary and disassociated nature of what has thus far been uncovered. In the hopes of better understanding this species, we used the histology and bone scaling of the pelvic limbs of Troodon and the modern emu to make inferences about its ontogeny. This resulted in the discovery of highly variable growth strategies in Troodon individuals, as well as further evidence that modern cursorial avians are not an apt modern analogue for Troodon ontogeny and locomotion.