Notiomastodon Notiomastodon Notiomastodon is an extinct proboscidean genus of gomphothere (a distant relative to modern Elephants) endemic to South America from the Pleistocene to the Holocene living for approximately . Proboscideans in South America were first described by Georges Cuvier in 1806 but he failed to give them specific names beyond "Mastodon". It was Fischer in 1814 who gave the “"mastodonte des cordillères"” specimen the first specific name ""Mastotherium hyodon"". In 1824, Cuvier gave the specific names of ""Mastodon andium"" to the ""mastodonte des cordillères"" specimen, and ""Mastodon humboldtii"" to the ""mastodonte humboldien"". Due to the Principle of Priority, this means
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