First evidence of spinal arthropathy and congenital block of the cervical vertebrae in Temnospondyli.

Despite recent reports, the fossil record of pathologies in vertebrates is still patchy in terms of phylogeny, geological age and paleogeography. Here, we report several cases of pathological vertebrae in several specimens of the Late Triassic temnospondyl Metoposaurus krasiejowensis from Krasiejów. The presence of cervical block vertebrae (atlas-axis complex) is the oldest such case reported for any fossil tetrapod and the first such case reported in temnospondyls. Spinal arthropathy (or spinal arthritis) is the first such case for a non-amniote. Based on different levels of fusion among the centra in the three specimens, this pathology revealed different stages of disease development. Finally, hemivertebra (congenital scoliosis) have been noted previously; however, this is the first example of scoliosis caused by hemivertebra in the genus Metoposaurus. These findings from the Upper Triassic site in Krasiejów allow for a better characterization of vertebral diseases in the fossil record. This was possible because of the very rich material of vertebrae from the Krasiejów Konzentrat Lagerstätte.