Mammoth fossil with its root: Elephas primigenius from the North Sea. Pleistocene 20000-10000 years 14X12 cm
Woolly mammoths had four functional molars at a time, two in the upper jaw and two in the lower jaw.
About 23 cm of the crown was in the jaw and 2.5 cm above. The crown was continuously pushed forward and upward as it wore down, comparable to a conveyor belt. A mammoth had six sets of molars during its lifetime, which were replaced five times. The first molars were about the size of a human's, 1.3 cm, the third was 15 cm long and the sixth was about 30 cm long and weighed 1.8 kg.
The molars grew larger and contained more ridges with each replacement.