Woolly Mammoth - Description

Description

The appearance of the woolly mammoth is probably the best known of any prehistoric animal due to the many frozen specimens with preserved soft tissue and depictions by contemporary humans in their art. Fully grown males reached shoulder heights between 2.7 and 3.4 m (9 and 11 ft) and weighed up to 6 tonnes (6,000 kg). This is almost as large as extant male African elephants, which commonly reach 3–3.4 m (9.8–11.2 ft), and is less than the size of the earlier mammoth species M. meridionalis and M. trogontherii, and the contemporary M. columbi. The reason for the smaller size is unknown. Female woolly mammoths averaged 2.6–2.9 m (8.5–9.5 ft) in height and were built more lightly than males. A newborn calf would have weighed about 90 kg (200 lb). These sizes are deduced from comparison with modern elephants of similar size. Though the mammoths on Wrangel Island were smaller than those of the mainland, their size varied, and they were not small enough to be considered "dwarves". It has been claimed that the last woolly mammoth populations decreased in size and increased their sexual dimorphism, but this was dismissed by a 2012 paper.

Woolly mammoths had several adaptations to the cold, most noticeably the layer of fur covering all parts of the body. Other adaptations to cold weather include ears that are far smaller than those of modern elephants; they were about 38 cm (15 in) long and 18–28 cm (7.1–11 in) across, and the ear of the 6–12 month old frozen calf "Dima" was under 13 cm (5.1 in) long. The small ears reduced heat loss and frostbite, and the tail was short for the same reason, only 36 cm (14 in) long in the "Berezovka mammoth". The tail contained 21 vertebrae, whereas the tails of modern elephants contain 28–33. Their skin was no thicker than that of present-day elephants, between 1.25 and 2.5 cm (0.49 and 0.98 in). They had a layer of fat up to 10 cm (3.9 in) thick under the skin, which helped to keep them warm. Woolly mammoths had broad flaps of skin under their tails which covered the anus; this is also seen in modern elephants.

Other characteristic features depicted in cave paintings include a large, high, single-domed head and a sloping back with a high shoulder hump, resulting from long spinous processes on the neck vertebrae. These features were not present in juveniles, which had concave backs like Asian elephants. Another feature shown in cave paintings was confirmed by the discovery of a frozen specimen in 1924, an adult nicknamed the "Middle Kolyma mammoth", which was preserved with a complete trunk tip. Unlike the trunk lobes of modern elephants, the upper "finger" at the tip of the trunk had a long pointed lobe and was 10 cm (3.9 in) long, while the lower "thumb" was 5 cm (2.0 in) and was broader. The trunk of "Dima" was 76 cm (2.49 ft) long, whereas the trunk of the adult "Liakhov mammoth" was 2 metres (6.6 ft) long. Few frozen specimens have preserved genitals, so the gender is usually determined through examination of the skeleton. Males were generally larger and had more robust skeletons and tusks. The best indication of sex is the size of the pelvic girdle, as the birth canal means the structure is always wider in females than in males.