Woolly Mammoth Fossils
PLEISTOCENE PERIOD: 250,000 - 10,000 years ago
Emerging 55 million years ago, the group of mammals called Proboscideans are identified by the presence of tusks and a trunk and include mammoths, mastodons and elephants. The oldest mammoth remains have placed the beginnings of the beasts in Africa but eventually, they migrated to Europe and Asia. Around 1.7 million years ago, the Ancestral mammoth began reaching North America and later evolved into the Columbian mammoth, otherwise known as the American mammoth.
Woolly mammoths (Mammuthus primigenius) were first recorded in Eurasian deposits of the second to the last Ice Age, approximately 150,000 years ago. Woolly mammoths descended from the Steppe mammoths (Mammuthus trogontherii). Over time, the cheek teeth of Woolly mammoths evolved into a design of more numerous and tightly arranged enamel plates with less thickness. The tusks of the Woolly mammoth developed a more dramatic curvature and their overall body size decreased. These changes were advantageous in surviving the increasingly cold conditions of the last Ice Age. Such teeth modifications enabled the Woolly mammoths to chew tougher tundra vegetation. The reduction of body size accompanied by the reduction of the ears and trunk along with the development of a thicker pelt enabled the mammoths to survive in the harshness of a frozen world.
A full grown Woolly mammoth stood around 10 - 12 feet high at the shoulder and weighed in at 6 - 8 tons. Despite connotations of the word "mammoth" indicating immense proportions, the Woolly mammoth is actually not the largest mammoth that ever lived. The Imperial mammoth was the largest and the North American Columbian mammoth was even larger than the Woolly mammoth. The Woolly mammoth was about the same size as a present day Indian elephant but with a layer of fat and fur.
Preserved carcasses have been found in frozen tundra which allows us to know what the heavy coat of the Woolly mammoth was like. Their fur was similar to that of the musk ox, consisting of long, dark hairs and fine under wool, with dark-gray skin and an insulating fat layer. It is most likely that Woolly mammoths molted in summer like Musk oxen. Another prominent feature of the Woolly mammoth was a high-domed skull with high-peaked shoulders resulting from the long spines of the neck vertebrae likely to anchor a large fat deposit.
Woolly mammoths had smaller ears and a shorter trunk than modern-day elephants. Many Woolly mammoths have been found with large, elaborately curved tusks. Both the males and females possessed tusks, but the females’ tusks were smaller. Tusks began to form at birth and continued growing throughout life, adding about a 1/4 inch a year in thickness as they grew. Most of the tusk is comprised of a material called dentin but in layman's terms, we call it ivory.
The undersides of Woolly mammoth tusks often show wear, suggesting that they were used in scraping snow and ice off ground cover vegetation during feeding. Woolly mammoths also use their tusks for protection against predators, attraction during mating and as a display of dominance to other Woolly mammoths. The longest tusk ever found was almost 16 feet and weighs 208 pounds.
Mammoths were herbivores. The teeth of a mammoth are amongst the most bizarre teeth of any animal ever known. From the side, they resemble an extended accordion and are made up of a row of vertically oriented attached plates that when worn, create a washboard-like grinding surface. This surface was ideally suited to grinding up hard-to-digest foods such as tough grasses and other thick vegetation. A mammoth has four teeth in its skull, two uppers (one on each side) and two lowers. Over the course of the life of the animal, six sets of teeth will grow, a worn set being pushed forward and out to make room for a new and unworn set.
This characteristic is still true of modern elephants. A baby mammoth at age 6 will have already had three sets of teeth. By 13 years of age, the fourth set emerges followed by a fifth set at age 27 years. The final set of teeth come in around 43 years of age and as it wears away, the animal eventually starves to death and dies on average between 60 and 80 years of age. Interestingly, the animal's life is limited by the fact that after the sixth set, no new teeth grow in to replace the final worn down set and the animal is no longer able to chew its food. Mammoth teeth can also tell us the age and species of the creature. Scientists can approximate age by comparing the length and width of the molars to corresponding age and tooth size charts from modern elephants. The species is determined by the number of ridges found in the first four inches of the flat chewing surface.
In the latter years of the last Ice Age, the Woolly mammoth co-existed with humans such as the Neanderthal and the Cro-Magnon people. Prehistoric cave paintings in France and Spain have been found with images of the Woolly mammoth including hunting scenes. Throughout world regions where Woolly mammoths existed at the same times as humans, kill sites have been discovered where mammoth carcasses had been butchered. At these sites, scientists have found both stone tools and mammoth bones displaying gashes and cuts, evidence of cutting and scraping by humans using these stone tools.
It is believed that the end of the last Ice Age and the warming of the Earth caused the Woolly mammoths to die out at the end of the Pleistocene Period. The DNA of an extinct wooly mammoth is 95% identical to an Indian elephant. With recent discoveries of wooly mammoth remains frozen in tundra, there are ongoing attempts to clone intact DNA with that of the modern Indian elephant.
Woolly mammoth remains have been found in northern regions of North America, Eurasia and Europe.
- copyright Paleo Direct, Inc. Images of the Woolly Mammoth skeleton were taken at the Naturalis Biodiversity Center, Holland