As palaeontologists, we are used to relying on the preserved hard parts of extinct organisms – shells, bones, teeth and so on – to reconstruct their appearance and adaptations in life. The reconstruction of soft tissue relies upon our knowledge of related living forms, plus clues such as the scars of muscle attachments on bones or shells. Exceptions include body outlines preserved in the fine-grained sediments of Lagerstätte, such as in the Eocene of Messel (Germany) or the Cambrian Burgess Shale (Canada); or, even more rarely, organisms preserved in 3D, of which the most familiar source is Tertiary amber.
Among mammals, the most celebrated case of exceptional preservation is provided by the carcasses preserved in permafrost in Siberia (Russia), Alaska (USA) and the Yukon (Canada), at localities lying almost exclusively north of the Arctic Circle (Lister and Bahn, 2007). Almost all date to the last glaciation, with radiocarbon dates typically in the range 50 to 10,000 years ago. Species from which partial or whole carcasses have been recovered include bison, horse, wolverine, woolly rhinoceros and, above all, the woolly mammoth. The reason for the preponderance of these is unclear, although it may partly be a matter of reporting bias, other species being considered less interesting or less valuable when discovered by local people.
Even so, not more than a dozen or so complete or largely complete mammoth carcasses have been recovered to date. While Siberian natives have doubtless been finding these remains for millennia, the first carcass to be scientifically studied was excavated in 1806 (Fig. 1) and brought back to St Petersburg, where it still stands in the Zoology Museum. However, by the time it was recovered, much of the flesh had decayed or been eaten by wolves – the specimen, known as the Adams mammoth after its excavator, is now a skeleton with some patches of skin and muscle remaining on the face and elsewhere (Fig. 2). In 1901, the Beresovka carcass was discovered, with much of its flesh intact, but it was encased in frozen ground and its extraction involved lighting fires around it in an attempt to melt the ice, and finally hacking it out in pieces. On the mounted skin in St Petersburg, one can still see the lines where it was stitched back together.
The majority of recovered finds have been made since the 1970s. Recovered in 1972, the Shandrin mammoth was remarkable for having 291kg of food still in its intestines, one of several individuals for which we have directly preserved evidence of diet (see below). Many of the other recovered individuals have been juveniles of various ages. The male baby mammoth nicknamed ‘Dima’, discovered in 1977, was the most complete individual known up to that time and the first to be subject to detailed scientific study, with internal organs and preservation of structure down to the cellular level.