Anachronisms in the Book of Mormon 1000 years before the Jaredite record in the Book of Mormon begins. The main point of contention is how late these animals were present in the Americas before becoming extinct. Various Mormon authors have cited evidence that North American mound-builder cultures were familiar with the elephant. The oldest mound-builder societies date to around 2000 BC. The mound builder/elephant controversy did not originate with the Book of Mormon. In "The Mound Builders, Their Works and Relics", author Stephen Dennison Peet cites instances of exhumed mastodon remains and arguments given for why the remains were believed to be contemporary with mound builders.
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