Abstract
AbstractMany dinosaurs may have shown ecological differentiation between hatchlings and adults, possibly because of the great size differential. The basal ceratopsian Psittacosaurus lujiatunensis is known from thousands of specimens from the Lower Cretaceous of China and these include many so‐called ‘juvenile clusters.’ During the early stages of ontogeny, P. lujiatunensis underwent a posture shift from quadrupedal to bipedal, and a dietary shift has also been postulated. In this study, we made a 2D mechanical analysis of the jaws of a hatchling and an adult to determine the differences between the two systems; we found some differences, but these were only modest. The adult was better suited to feeding on tough plant material than the hatchling, based on its higher values of absolute and relative bite forces and higher values of mechanical advantage, but there were no substantial shifts in jaw shape or function.
Highlights
Many dinosaurs may have shown ecological differentiation between hatchlings and adults, possibly because of the great size differential
The aim of this paper is to test whether P. lujiatunensis underwent an ontogenetic dietary shift based on a biomechanical study of the jaws and teeth of juvenile and adult specimens
Hedrick & Dodson (2013) suggested identity between the species P. lujiatunensis and P. major, a synonymy first suggested by Erickson et al (2009) on circumstantial evidence, but which was rejected by others (Napoli et al 2019)
Summary
Many dinosaurs may have shown ecological differentiation between hatchlings and adults, possibly because of the great size differential. AMONG large tetrapods, dinosaurs exhibited a remarkably great disparity in size between hatchlings and adults. Psittacosaurus is unusual in that it comprises many species (19 have been named, of which up to 10 are accepted as valid; Sereno et al 2010; Napoli et al 2019) as well as many specimens, with some species represented by thousands of individuals (Zhao et al 2013a, b). This is why Psittacosaurus has been chosen to name a fauna (Dong 1993) and a biochron (Lucas 2006) spanning the Barremian to Albian (129–100 Ma).
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