Mandibular pathologies in Notiomastodon platensis (Ameghino, 1888): Insights into chronic osteomyelitis and its implications for the health of Pleistocene proboscidean from South America

Notiomastodon platensis (Ameghino, 1888) is the most widely distributed proboscidean species in the Quaternary of South America. Over the past few decades, various pathological conditions of the axial skeleton have been described in this species; however, no cases of mandibular diseases has been reported to date, despite their common occurrence in extant proboscideans. In this study, we document signs of mandibular diseases in two N. platensis individuals from the Pleistocene of Argentina. The first individual exhibits bony swelling, cloaca and solid periosteal reaction, likely associated with a fractured molar. The second specimen shows extreme molar crown wear, pulp cavity exposure, and the formation of a periapical abscess, likely resulting from pulp infection due to dental attriction. Both cases, though differing in origin, are diagnosed as secondary chronic osteomyelitis of the mandible, an infectious process that would have impaired feeding, potentially leading to malnutrition, weakness, and contributing to the mortality of these individuals.