A funny thing happened on the social media site, Mastodon. Someone made a comment about the name of the site and illustrated not a Mastodon, but a Mammoth. This was pointed out to them by someone in the know. How you tell the difference, I didn’t know, so I thought I’d have a crack at finding out, as well as how they relate to modern elephants.
When I was much younger, everybody knew that there were two species of extant elephant, the African and Asian elephants. Now we know better. Elephants in Africa belong to the genus Loxodonta and are divided into two species; the African savanna elephant (Loxodonta africana) and the smaller African forest elephant (Loxodonta cyclotis). Even though the smaller forest elephant was known from about 1900, it was long thought to be a subspecies of the bush elephant. However, detailed morphological and DNA analysis only a couple of decades ago has shown that they are two distinct species and diverged from one another a couple of million years ago1. The forest elephant is now critically endangered mostly due to poaching and habitat loss2. The Asian elephant belongs to a different genus (Elephas) and there is only a single species, Elephas maximus3.
These genera (Loxodonta and Elephas) are the only two surviving genera of the Family Elephantidae which is the only extant family of the Order Proboscidea1. There are, of course, several extinct elephants, with as many as seven species of Elephas known from fossil remains in various parts of Asia and east Africa3, and four of Loxodonta known from fossils in various parts of Africa1, 3.
Proboscideans evolved in Africa, with the oldest fossil of a proboscidean belong to a genus called Eritheriumknown from fossils dating from the latter part (61-58 million years ago [mya]) of the Paleocene (about 66-56 mya) found in Morocco. The animal was quite small, and stood only about 20 cm tall at the shoulder and probably weighed about 5-6 kg4. Proboscideans increased in size during the Eocene (56-34 mya) and the early part (34-28 mya) of the succeeding Oligocene (34-23 mya)3.
The Mammutidae is an extinct family of proboscideans which appeared in the Oligocene and survived until the beginning of the Holocene (about 11,000 years ago). The most well known genus from the family is Mammut, the genus of mastodons5. This genus is known from North and Central America and the most well known species is the American mastodon, Mammut americanum, which is known from as far north as Alaska to as far south as California, Florida and Honduras. They were forest-dwellers and browsers and were unlikely to have been as hirsute as the woolly mammoth6.
The Mastodons are one of what is called the basal or earliest groups of Proboscideans and they are not particularly closely related to modern elephants, but more so to extinct families such as the Gomphotheriidae and the Stegodontidae. Mammoths, on the other hand, are quite closely related to modern elephants and appeared about 5 million years ago, early in the Pliocene (5.3-2.6 million years ago). In fact they are in the same family, the Elephantidae, as the three species of modern elephants. The genus to which the mammoths belong, Mammuthus, was likely to have evolved in South Africa expanded their range over much of Eurasia before migrating into North America about 1.5 million years ago during the Pleistocene (2.6 million to 11,000 years ago). Sea levels were much lower then, and Asia was connected to North America. This gave rise to the Columbian Mammoth (Mammuthus columbi) which occupied most of what is now the United States and Central America until the end of the Pleistocene (about 11,000 years ago). The last species of mammoth to evolve was the woolly mammoth, Mammuthus primigenius. It appeared about 400,000 years ago in east Asia and spread over much of northern Europe, surviving on Wrangel Island in the Arctic Ocean until as recently as 4,000 years ago7.
Despite the superficial resemblance of these elephantine beasts, mastodons were shorter and stockier than mammoths, had lower, flatter heads and had shorter, straighter tusks. Mastodons were wood browsers and their molars have pointed cones specially adapted for eating woody tissue. Mammoths were grazers, and their molars have flat surfaces for eating grass8, 9.
So there you have it, a potted history of mastodons and mammoths and a very brief explanation of how they differed.