An Injured Psittacosaurus (Dinosauria: Ceratopsia) From the Yixian Formation (Liaoning, China): Implications for Psittacosaurus Biology

Abstract

We describe a Psittacosaurus specimen from the Lujiatun beds of the Yixian Formation in Liaoning, China with an abnormality on its left fibula. Although a large number of Psittacosaurus specimens are known, only a single example of a pathologic Psittacosaurus has been previously noted. The specific pathology in the current specimen is believed to be a healed fibular fracture as assessed through a combination of gross morphology, microcomputed tomography (microCT), and histology data. The fracture can be identified using microCT, but the degree of remodeling and the stage of fracture repair are best determined histologically. The fracture callus is made up of radially oriented spokes of woven bone in a cartilage matrix and the original cortical bone prior to the fracture has been largely eroded. A transverse histologic section taken at the level of the fracture shows the displacement of the proximal and distal parts of the fibula. The Psittacosaurus appears to have survived the break considering the deposition of circumferential non-pathologic bone at the periosteal surface outside of the callus. The combination of gross morphological description, microCT data, and histologic data allowed for a full diagnosis of the abnormality. While some previous authors have preferred gross morphological description above other methods for assessing paleopathologies, it is evident based on this specimen that an amalgam of techniques provides greater clarity to paleopathology diagnoses.

Silencing long non‐coding RNA MEG3 accelerates tibia fraction healing by regulating the Wnt/β‐catenin signalling pathway

“…Furthermore, blurring of fracture margins and reactive sclerosis are known to be the earliest signs of healing in both modalities . The fracture callus is radially composed of oriented spokes of woven bone in a cartilage matrix and the original cortical bone before the fracture largely erodes . Moreover, the current study revealed that silencing MEG3 promotes ossis repatency and callus reconstruction, which suggests that silencing MEG3 promotes fracture healing.…”

Description and etiology of paleopathological lesions in the type specimen of Parasaurolophus walkeri (Dinosauria: Hadrosauridae), with proposed reconstructions of the nuchal ligament

“…The axial skeleton is rigidly fixed to the panel mount, and the postcranial elements could not be removed to facilitate an internal analysis via CT scanning. As reported by several authors (Anné et al, 2015, 2016; Ekhtiari et al, 2020; Hedrik et al, 2016; Jentgen‐Ceschino et al, 2020; Redelstorff et al, 2015), diagnoses of fossilized injuries and diseases can be improved through the use of internal analytical techniques such as histology, (micro)CT scans, and synchrotron. Unfortunately, ROM 768 cannot be disassembled from the mount and, therefore, this study solely focuses on the external morphology while bearing in mind the difficulties of providing detailed diagnoses using such an approach.…”

First Documented Pathologies in Tenontosaurus tilletti with Comments on Infection in Non-Avian Dinosaurs

“…Multiple studies have shown the utility of micro-CT and CT scanning as a non-invasive way of studying the internal morphology of bones 22,28,30,31 . The application of CT scanning in this diagnosis was integral for narrowing the range of possible etiologies.…”

“…Rather, it suggests that the response to osteomyelitis in dinosaurs and mammals might produce the same osseous morphology. Two studies—Emslie and Nade 31 , and Tully, et al . 36 —noted that osteomyelitis in birds follows a similar pathogenesis to mammals and can produce similar osseous responses in analogous elements.…”