Mastodon

The mastodonts (Mastodontoidea) are a taxon no longer in use for a superfamily of proboscideans. This group originally included the families of Gomphotheria (Gomphotheriidae), Mammutidae (Mammutidae; in German sometimes also called "Echte Mastodonten") and Stegodontidae (Stegodontidae). The name Mastodontoidea was introduced by Henry Fairfield Osborn (1857-1935) in 1921 and goes back to Mastodon, which was originally used in 1817 by Georges Cuvier (1769-1832) for a proboscidean of the Gomphotheria, today called Gomphotherium angustidens (however, Cuvier had already described it as mastodonte à dents étroites in 1806). The name is from the Greek μαστός (mastos, breast) and οδον (odon, tooth). It refers to the cheek teeth marked by cusps, which, when viewed from the side, resemble a woman's breasts ("breast teeth").

A common feature within the group of mastodons was their already distinctly elephantine appearance, although they tended to be more elongated and lower in build overall, and possessed longer and flatter skulls. Early forms, however, were relatively small and quite short-legged. Furthermore, their bumpy dental structure clearly distinguished them from elephants with their lamellar teeth. In addition, unlike modern elephants, numerous representatives had elongated tusks in both the lower and upper jaws, which had evolved from the incisors.

Cladistic studies revealed that the mastodonts do not represent a closed lineage group (monophylum). Instead, they represent three different evolutionary lineages, each branching individually from the elephant lineage (Elephantidae). For this reason, the mastodonts are now assigned to three different superfamilies. The mammothids now belong to the superfamily Mammutoidea, the gomphotheria to the superfamily Gomphotherioidea, and the stegodonts to the superfamily Elephantoidea. The latter also includes the elephants. All three superfamilies belong to the Elephantimorpha. Today, the term mastodon is often used colloquially only for the American mastodon, while mastodon usually occurs only as a scientific name suffix (such as Notiomastodon, Stegomastodon or Sinomastodon).