Tuberculosis-like infectious spondylitis in a cervical vertebra of a plesiosaur from the Upper Cretaceous of Patagonia, Argentina

M. TALEVI; B. ROTHSCHILD; MITIDIERI, MATÍAS; FERNÁNDEZ MARTA, S.

Congreso; 9th 9th International Meeting on the Secondary Adaptation of Tetrapods to Life in Water; 2021

Paleopathological studies have been used to understand the history of injury and disease inextinct populations, their putative cause, and on this basis, some infer paleoecology andbehavioral aspects. Paleopathologies are generally identified if they damage the skeleton. Themost common in the zoological/paleontological record are traumatic injuries, post-traumaticmalformations, modification of bone tissue from infection, congenital defects, andneoplasms. Although pathologies in plesiosaurs are recognized since the 1870s, and variousdiseases have been reported (e.g., septic necrosis, avascular necrosis, erosive osteoarthritis,vertebral fusion, and tooth-marked bones), reports of infectious diseases are stillcomparatively scarce. Here we report the pathological cervical vertebra of a plesiosaurrecovered from the Maastrichtian (Late Cretaceous) of Argentinian Patagonia. The specimenMML-PV 1305 is explored macroscopically and by computerized microtomography. Theanterior external surface shows a taphonomic artifact (in the form of cracks in thesubchondral bone with central loss) as well as an elliptical, subchondral erosion with minimalnew bone formation and a slight adjacent filigree reaction. The right anteroventral surfaces ofthe centrum bears an erosive process with a minimal bone reaction and alterations have theappearance of space-occupied masses. On the left anteroventral surface of the centrum, thereare abnormal vascular channels, associated with a groove just ventral to the articular surface.X-ray examination reveals a central lytic area with weakened and collapsed trabecular bone.The combination of these features indicates that the pathological aspect of the vertebra is dueto an infection. The pattern of bone abnormalities is indistinguishable from that described inPleistocene mammal skeletons affected by the granulomatous tuberculosis infection andanalogous to the abnormal ribs and cervical vertebrae of an eosauropterygian from theMiddle Triassic. The latter is also identified as turberculosis-like pneumonia. The casereported herein represents the first record of tuberculosis-like infection in a plesiosaur. As thevertebra was not part of an associated skeleton, it cannot be determined if the cause of deathof the plesiosaur is unrelated or secondary due to compromised hunting ability (due to limitedneck mobility) or the result of infection-related organ failure.