Psittacosaurus hatchlings with gastroliths

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper not yet mentioned:

(Note that this article should be free in final form on the Chinese website in a few months.)

Longhan Wang, Xiaobo Li, Quanbo Wen, Jun Chen & Robert Reisz (2025)
Gastroliths in hatchling Psittacosaurus show early dietary habits
Science China Earth Sciences (advance online publication)
doi: https://doi.org/10.1007/s11430-025-1759-4
https://link.springer.com/article/10.1007/s11430-025-1759-4

Psittacosaurus is one of the most abundantly preserved, widely distributed Early Cretaceous dinosaurs and is represented by hundreds of complete individual specimens, with most age classes ranging from hatchlings to adults. They are therefore ideally suited for paleobiological studies of growth rates, locomotion, and reproductive biology. Interestingly, subadults and adults are known to have gastroliths for assisting in processing plant materials, leading to the assumption that they acquired them late in their life cycle. In order to understand their feeding behaviour, we focused this study on a cluster of 13 complete small skeletons of Psittacosaurus with gastroliths from the Cretaceous Yixian Formation near Lujiatun Village in Liaoning Province, China. Through the analysis of their long bone histology, we determined that all these individuals were less than 1 year old. All individuals in the cluster were found to possess gastroliths of predominantly igneous origin, the first report of gastroliths in Psittacosaurus of such an early ontogenetic stage. This finding supports the startling conclusion of precocious acquisition of gastroliths in Psittacosaurus, and indicates that hatchlings and adults shared similar dietary habits in this dinosaur. The presence of these gastroliths provides valuable insights and contributes significantly to the reconstruction of the paleobiology of this keystone herbivorous dinosaur.