Mastodon group consisted of adult females and young, living in bonded groups called mixed herds. The males abandoned the mixed herds once reaching sexual maturity and lived either alone or in male bond groupings. As in modern elephants, there probably was no seasonal synchrony of mating activity, with both males and females seeking out each other for mating when sexually active. Mastodons have been characterized as predominantly browsing animals. Most accounts of gut contents have identified coniferous twigs as the dominant element in their diet. Other accounts (Burning tree mastodon) have reported no coniferous content and suggest selective feeding on low,
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