The standard NALMAS used in the arrangement of the UCMP collection are
listed below with reference to their appropriate epoch for general reference.
Hemphillian (extends into Pliocene)
Arikareean (extends into Miocene)
Wasatchian (may extend into Paleocene)
For a detailed current discussion of the Land Mammal Age boundaries, read
Woodburne, M.O. and C.C. Swisher III. 1995. Land mammal high-resolution geochronology, intercontinental overland dispersals, sea level, climate, and vicariance, pp. 337-364 in W.A. Berggren, D.V. Kent, M-P. Aubry and J. Hardenbol (eds.) Geochronology, Time Scales, and Global Stratigraphic Correlations: Unified Temporal Framework for an Historical Geology, SEPM Spec. Pub. no. 54