Research on the biology, especially on life history, of insular endemics is of great importance because they are under specific ecological pressures: low extrinsic mortality and resource limitation. We reconstruct some biological traits of an extinct ochotonid, Prolagus apricenicus from Gargano (Late Miocene; Italy). The extinct mainland Prolagus cf. calpensisis analyzed for comparisons. Our results predict a mass of 350 g for P. cf. calpensis, 280 for P. apricenicus (from Cava Dell’Erba, F1 site), and 600 for P. apricenicus (from Cava Fina, F8 site). Though a thorough histological analysis was hampered by the poor preservation of the material, skeletochronology of P. apricenicus from F1 indicates a longevity of at least around 7 years for this population. This suggests a slower life history than expected from body size for P. apricenicus compared with extant ochotonids.