Few pathological cases have been identified in fossils of small mammals. Here we report the
most ancient paleopathological evidence identified in a lagomorph (Ochotonidae, middle
Miocene). The tibiofibular bone was macro- and microscopically inspected to provide
a diagnosis, an etiology, and its possible relationship with the individual’s cause of death.
Osteogenesis (reactive bone growth) and osteolysis, processes related with neoplasms and
infections, are identified in the abnormal bony region. Its location (juxta-articular) and
morphology allow us to identify it as a joint infection (septic arthritis) consequential of a
violent mechanism, such as a bite. Both the origin of bone accumulation (avian pellets) and
the poor vital state of the specimen (with a joint infection) point to predation as the most
probable cause of death. Up to now, lagomorph paleopathologies had only been described
in insular populations, and the present one is the first evidence in a mainland specimen.
