An article published in the journal “PeerJ” reports a study on the development of the skull structure of Psittacosaurus lujiatunensis during its growth. A team led by Claire Bullar of the British University of Bristol examined dozens of fossils belonging to this species focusing in particular on their skulls to understand their growth. This also offers more information on their locomotion changes since they were born quadrupeds but were bipeds in adulthood.
The genus Psittacosaurus has been widely studied thanks to the discovery of hundreds of fossils in various parts of Asia with an age between 126 and 101 million years and therefore dating back to the Cretaceous period. They were cousins of the famous Triceratops, which however was a normal quadruped. A research on the change of locomotion and posture in Psittacosaurus lujiatunensis was already reported in an article published in the journal “Nature Communications” in June 2013 and two members of that team, Qi Zhao and Michael J. Benton, also participated in this new research focused on this dinosaur’s skull changes during its growth.
Many fossil skulls were subjected to a high quality CT scan to obtain 3D models. Their examination revealed that during the maturation the juvenile specimens of Psittacosaurus lujiatunensis pointed their head forward, not downwards, indicating that at the age of a few years they already had a bipedal locomotion. Other evidence of that change comes from the skull’s shape, which shows their brain development, and in their limbs development, with their hindlimbs which became far stronger after a few years.
The image (Claire Bullar et. Al. https://doi.org/10.7717/peerj.7217/fig-32 ) shows the posture of a hatchling Psittacosaurus lujiatunensis (A), a juvenile (B) and an adult (C). In particular the position of the head is shown.
Among dinosaurs, it was more common to be born bipeds and then become quadrupeds with growth, while in the species of the genus Psittacosaurus the opposite occurred. It’s a reason why they have been studied over the years, including the species Psittacosaurus lujiatunensis. Professor Michael Ryan of Carleton University, Ottawa, Canada, one of the authors of the research, explained that the transition from biped to quadruped occurred when a dinosaur became very large but Psittacosaurus lujiatunensis reached two meters in length and perhaps as a biped could run faster to escape predators.
The dinosaurs of the genus Psittacosaurus are also interesting for other reasons: for example, an article published in the journal “Current Biology” in September 2016 described the camouflage abilities of one of them. Modern technologies give the possibility to perform in-depth fossil analyzes thanks to high quality scans and 3D reproductions, in this case to better understand the characteristics of these curious dinosaurs.
