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
Extinct radionuclide Extinct radionuclide An extinct radionuclide is a radionuclide that was formed by nucleosynthesis before the formation of the Solar System, about 4.6 billion years ago, and incorporated into it, but has since decayed to virtually zero abundance, due to having a half-life shorter than about 100 million years. Short-lived radioisotopes that are found in nature are continuously generated or replenished by natural processes, such as cosmic rays (cosmogenic nuclides), background radiation, or the decay chain or spontaneous fission of very long-lived isotopes such as uranium or thorium. Short-lived isotopes that are not generated or replenished by natural processes are not