Four type specimens and three other important fossils, all mammalian, which were apparently lost to science, have recently been rediscovered in an old building located in Mexico City. Recovered types include Glyptodon mexicano, Mastodon oligobunis, Equus conversidens, and Equus (Hesperohippus) mexicanus. The three important nontypes are a lower jaw of Arctodus simus, a partial skull of Euceratherium collinum, and a partial skull of Bison antiquus. All the specimens have been recataloged and are now in the Museum of Paleontology, Institute of Geology, at the University of Mexico.