Mastodon largest male specimens, the 35-year-old AMNH 9950 was tall and weighed , while another was tall and weighed . Like modern elephants, the females were smaller than the males. They had a low and long skull with long curved tusks, with those of the males being more massive and more strongly curved. Mastodons had cusp-shaped teeth, very different from mammoth and elephant teeth (which have a series of enamel plates), well-suited for chewing leaves and branches of trees and shrubs. Based on the characteristics of mastodon bone sites, it can be inferred that, as in modern proboscideans, the mastodon social
Second voyage of HMS Beagle tooth among the Punta Alta fossils. This discovery was later explained as part of the evolution of the horse. The "soft as cheese" "Mastodon" bones at the Paraná River were identified as two gigantic skeletons of "Mastodon andium", and mastodon teeth were also identified from Santa Fé and the Carcarañá River. The pieces of spine and a hind leg from Port S. Julian which Darwin had thought came from "some large animal, I fancy a Mastodon" gave Owen difficulties, as the creature which he named "Macrauchenia" appeared to be a "gigantic and most extraordinary pachyderm", allied to the "Palaeotherium", but