Arthritis in a glyptodont (Mammalia, Xenarthra, Cingulata).

Arthritic lesions have been frequently diagnosed in the fossil record, with spondyloarthropathy (a type of erosive and pan-mammalian arthritis) being one of the most common types described to date for mammals, though not restricted to this group. Here, we identify spondyloarthropathy in fossil bones from the late Pleistocene in Brazil assignable to a large glyptodont individual. Bone erosions in the peripheral joints (viz., the ulna, radius, left femur and tibiae-fibulae) associated with osteosclerosis allow the diagnosis of spondyloarthropathy. The presence of osteophytes in seven bones of the forelimbs (viz., the ulna and radius) and hind limbs (viz., the tibiae-fibulae, left femur and patellae) and a subchondral cyst in one element (viz., the left femur) indicate secondary osteoarthritis. A calcified deposition on the articular surface of the left patella indicates the presence of calcium pyrophosphate deposition disease, which, like the observed osteoarthritic alterations, likely represents a complication of spondyloarthropathy. This is the first report of spondyloarthropathy for xenarthrans.

Neck osteoarthritis in Eremotherium laurillardi (Lund, 1842; Mammalia, Xenarthra) from the Late Pleistocene of Brazil.

Paleopathological analyses of Brazilian Quaternary mammals remain scarce. However, this type of study can shed light on several paleoecological issues in vertebrate paleobiology and taphonomy. Here, we describe and diagnose a pathology on an axis of a ground sloth Eremotherium laurillardi (Lund, 1842) from Pernambuco State, Brazil. Through the identification of osteophytes, we define an osteoarthritic lesion in the atlantoaxial joint (C1-C2), which is unrelated to body weight support. Thus, this paper reports a peculiar allocation of osteoarthritis in a mammalian skeleton. We did not attribute such alteration to calcium pyrophosphate deposition disease (CPPD) because the bone elevation occurs only on the borders of the lateral articular facets of the axis, and not on the joint surface. This analysis shows that osteoarthritis can also occur in regions of vertebral column that are not weight-bearing, which is one of the main predisposing factors for this disease.