Reshaping a woolly rhinoceros: Discovery of a fat hump on its back

Until now, a key question in reconstructing the appearance of the woolly rhinoceros has remained open: why did various Paleolithic artists often depict this animal with a hump on its back? Previous findings of mummies of this rhinoceros either had no hump or this area of the carcass was damaged. In this study, we describe the discovery of a subadult Coelodonta antiquitatis mummy (4–4.5 years old) from the permafrost of Yakutia. This is the first time that the presence of a hump in the neck and withers area has been reliably established. The hump of the studied rhinoceros measures 36 cm in length, 13 cm in height, and 14 cm in thickness, and is filled with adipose tissue. The dimensions of the subcutaneous and hump adipocytes probably indicate that the hump was filled with white fat. The presence of a fat hump in the woolly rhinoceros represents a distinctive adaptation that is not typical of the extant large mammals in the northern latitudes and likely contributed to their survival during the harsh winters of the Ice Age. This discovery shows that Paleolithic artists from Chauvet Cave made strikingly accurate depictions of the exterior of a woolly rhinoceros.