Collections also include several specimens of rare and highly controversial remains that may represent the oldest angiosperm plants in North America. Typical plants at that time, such as cycads and conifers, had spores; most plants today have seeds within a fruit.  From the Late Miocene to the Early Pleistocene, fossils of the Texas Panhandle reflect a savannah-like environment similar to modern plains in Africa. 

Three of the North American Land Mammal Ages (suites of animals) are named for the Texas Panhandle—Clarendonian, Hemphillian, and Blancan.  Although many mammal species loosely resemble modern forms, like horses, rhinos, camels, and elephants (mammoth and mastodon), others are more surprising such as an enormous, clawed ground sloths; a deer with a slingshot-shaped structure on its nose; saber-tooth cats; giant terrestrial tortoises; and glyptodons, looking like a 10-foot-long, 3-foot high armadillo/turtle hybrid. 

These extensive collections are largely the result of Federal works projects that were directed by museum personnel during the 1930s and 1940s.  Recent additions provide wonderful study specimens from different times and areas, filling in gaps in the fossil collection.