Columbia subject headings:
Harvard subject headings:
Brontotheriidae--West (U.S.)
Paleontology--Paleogene
Paleontology--West (U.S.)
Perissodactyla, Fossil--West (U.S.)
Ungulates, Fossil--West (U.S.)
Ungulates, Fossil.
Princeton subject headings:
Paleontology--West (U.S.)
Perissodactyla, Fossil.
Ungulates, Fossil.