There are four identifiable specimens of Gomphotherium in the collections of the New
Mexico Museum of Natural History and Science in Albuquerque, all collected in New Mexico. The
most diagnostic specimen, NMMNH P-28972, consists of a nearly complete skull of a young adult
female found in the Pojoaque Member of the Tesuque Formation (late Barstovian). NMMNH P-19204
is an incomplete skull and lower jaws of a more mature, presumably female, individual with associated left forelimb elements recovered from the Charnita Formation (Hemphillian). Both of these specimens were collected in the Espanola basin near Espanola. A third, less diagnostic specimen (NMMNH P-3694) consists of an incomplete left lower jaw of a juvenile Gomphotherium collected from the northern Albuquerque Basin, probably above the Zia Formation and also of probable late Barstovian age. A fourth spcimen (NMMNH P-25280) is described by Morgan and Williamson elsewhere in this volume. All North American specimens of Gomphotherium are currently assigned to the species G. productum. However, the two adult specimens in the NMMNH collection are relatively small (M3 length/width <140/<80 mm) and fall within a more restricted definition of G. productum. Larger Gomphotherium collected from the Espanola basin possess molars up to 50% larger than G. productum sensu stricto and may represent a different species. The name G. pojoaquensis is available for this larger taxon from the Pojoaque Member, and G. riograndensis is available for the large Chamita Formation gomphothere
