Mammoth and woolly rhino are two iconic species of the ice age. Mammoth in particular is one of the most studied and perhaps best understood of the Pleistocene megafauna. In part this is due to abundant and detailed discussion of their skeletal anatomy, but also thanks to unique preservation of frozen carcasses from present day Siberia. A new study published in Quaternary Science Reviews sheds new light on the character and function of the hair and coat from both mammoth and woolly rhino, aiming to explain their adaptation to colder climates.
For this study the authors studied 6 hairs from carcasses frozen in the Siberian permafrost ranging in dates from 46,900 to 5,930 BP. In addition, these were compared to modern day elephantid hair samples. The paper details how most animal coats have three types of hairs: overhairs, guard hairs and underhairs, helping to regulate temperature. The authors challenge the view that these animals had coats that were uniform in colour.
Rather, their findings suggest a variation in colouration with long, largely colourless overhairs underlain by guard hairs that ranged from brown to brown/red in colour. The final layer of underhairs were numerous and again, largely colourless. Interestingly, the authors identify multiple medullae-like features within the hairs from both mammoth and woolly rhino that in combination with the overall structure of their coats could have helped both species to survive the cold, harse conditions during the ice ages. The similarity between the two species suggest a convergent evolutionary path. Having an effective coat would have helped both megafaunal species to not just survive the cold environment, but to maximise, and efficiently utilise the limited calories obtained during leaner months.
The detailed macro and microscopic analyses not only illustrated interesting morphological features but also provided information on the taphonomy of these carcasses. The authors highlight the presence of insect activity, consuming the keratin from the hair, both ante and post-mortem. This raises the possibility that some of these carcasses began to rot prior to becoming frozen, which has not been highlighted previously.
Tridico, S.R., Rigby, P., Kirkbride, K.P., Haile, J., Bunce, M. 2014. Megafaunal split ends: microscopical characterisation of hair structure and function in extinct woolly mammoth and woolly rhino. Quaternary Science Reviews. 83: 68-75.