First report of a skeletal pathology of a mosasaur from the upper Cretaceous of Marambio Island, Antarctic Peninsula

TALEVI, MARIANELLA; ROTHSCHILD, BRUCE; FERNÁNDEZ, MARTA; REGUERO, MARCELO; MITIDIERI, MATÍAS

La Plata

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2019

Asociación Paleontológica Argentina

Paleopathological studies have been used to understand the history of injuries and diseases in extinct forms. Examples of paleopathologies have been widely observed and recognized among fossil vertebrates, including dinosaurs and various marine reptiles. Paleopathology studies represent a vast field of novel information in etiological terms and insight to resulting limitations affecting behaviour and provide a glimpse of the possible survival strategies under which these reptiles lived. Northern Patagonia and the Antarctic Peninsula have rich records of Upper Cretaceous marine reptiles. However paleopathology?s have not been previously reported from these abundant and diverse marine reptile assemblages. We describe a left scapula belonging to a juvenile mosasaurs from the upper Maastrichtian of Marambio Island (Seymour Island), Antarctic Peninsula, representing the first report of a skeletal pathology of a mosasaur from the southern hemisphere. Macroscopic examination of the scapula revealed a deeply excavated and expanded gleno-humeral joint with adjacent linear disruption. X-ray examination revealed a deep excavation expanding the glenoid fossa, with disorganized subchondral bone and a focal spherical defect. The diagnostic considerations are infectious arthritis and spondyloarthropathy. The articulation of the scapula and humerus was disrupted by the glenoid fossa expansion, compromising its normal function as a fulcrum. The limb was thus rendered flail, unable to contribute to propulsion or directionality (steering). Although not directly related to the mosasaur death, this condition may have contributed to the demise of the animal by reducing its effectiveness at obtaining food or increasing susceptibility to fatal disease, additional injury, or even predation.