Two types of bone necrosis in the Middle Triassic Pistosaurus longaevus bones: the results of integrated studies.

Dawid Surmik,Mateusz Dulski,Bruce M Rothschild,Katarzyna Janiszewska

doi:10.1098/rsos.170204

Abstract

Avascular necrosis, diagnosed on the basis of either a specific pathological modification of the articular surfaces of bone or its radiologic appearance in vertebral centra, has been recognized in many Mesozoic marine reptiles as well as in present-day marine mammals. Its presence in the zoological and paleontologic record is usually associated with decompression syndrome, a disease that affects secondarily aquatic vertebrates that could dive. Bone necrosis can also be caused by infectious processes, but it differs in appearance from decompression syndrome-associated aseptic necrosis. Herein, we report evidence of septic necrosis in the proximal articular surface of the femur of a marine reptile, Pistosaurus longaevus, from the Middle Triassic of Poland and Germany. This is the oldest recognition of septic necrosis associated with septic arthritis in the fossil record so far, and the mineralogical composition of pathologically altered bone is described herein in detail. The occurrence of septic necrosis is contrasted with decompression syndrome-associated avascular necrosis, also described in Pistosaurus longaevus bone from Middle Triassic of Germany.

Highlights

Pistosaurs (Pistosauridae) are marine reptiles, considered as a transitional form between Triassic stemsauropterygians, which inhabited near shores, and advanced, open marine Jurassic and Cretaceous plesiosaurs
Avascular necrosis is common in post-Triassic sauropterygians, indicating that they were susceptible to decompression syndrome because of prolonged and repetitive diving behaviour in these marine reptiles
Complete humerus from Bindlach, ascribed to Pistosaurus longaevus, with collapse of the articular surface defect of the type seen with avascular necrosis from bends was examined

Summary

Introduction

Pistosaurs (Pistosauridae) are marine reptiles, considered as a transitional form between Triassic stemsauropterygians, which inhabited near shores, and advanced, open marine Jurassic and Cretaceous plesiosaurs. DCS causes necrosis of bone (referred to as avascular necrosis, AVN), manifesting macroscopically as bone infarction and subsidence of the proximal articular surfaces of humeri and femora. Such subsidence is the direct evidence of decompression syndrome [14]. Avascular necrosis is common in post-Triassic sauropterygians, indicating that they were susceptible to decompression syndrome because of prolonged and repetitive diving behaviour in these marine reptiles

Results

Discussion

Conclusion