Mastodon have been no reports of currently recognized "Mammut" species outside of North America according to Paleobiology database (which does not recognize "M. borsoni"). However, the status of "Mammut" or "Zygolophodon borsoni" in the literature appears equivocal. "Mammut" is a genus of the extinct family Mammutidae, related to the proboscidean family Elephantidae (mammoths and elephants), from which it originally diverged approximately 27 million years ago. The following cladogram shows the placement of the American mastodon among other proboscideans, based on hyoid characteristics: Over the years, several fossils from localities in North America, Africa and Asia have been attributed to "Mammut", but
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