Columbia subject headings:
Harvard subject headings:
Geology, Stratigraphic--Cenozoic
Geology--North America
Mammals, Fossil.
Paleontology--Cenozoic
Paleontology--North America
Princeton subject headings:
Geology, Stratigraphic--Cenozoic.
Geology--North America.
Mammals, Fossil.
Paleontology--Cenozoic.
Paleontology--North America.