Mastodon fossil skeleton. 19th-centry illustration of a mastodon fossil skeleton. Drawn by US naturalist Titian Ramsay Peale (1799-1885) and published in January 1821. Peale's father Charles Willson Peale founded a museum in 1786 in Philadelphia, with the Peale Museum in Baltimore, Maryland, USA, established in 1814. Titian Peale, helped with collecting and preserving specimens for display in the museum. This is the first near-complete mastodon specimen, first put on display by Charles Willson Peale in 1801. Mastodons an extinct part of the elephant evolutionary tree, lived from 20 million to 12,000 years ago.