Mammoth tooth fossils. Fossilised molar teeth from juvenile mammoths (Mammuthus sp.), showing the structure of the chewing surface (ridges). Mammoths were large mammals found across North America, Europe and Asia from the Pliocene Epoch (around 4.8 million years ago) to the Pleistocene epoch (around 4500 years ago). They had six pairs of molars grow into their lower and upper jaw during their lifetime. Each pair was slowly grounded down and then replaced by a bigger set. When the final pair was finished, at about 60 years of age, the animal was no longer able to chew its food and would die from starvation. These specimens were found at the bottom of the North Sea and range in size from 7 to 20cm.