Age assignments were taken from the original publications, then updated to conform to Tedford et al. (2004), based on the trail of information that could be followed through the literature regarding the stratigraphic position of specimens. Inasmuch as possible, actual stratigraphic context was considered in making age assignments.
Tedford, R. H., L. B. Albright, A. D. Barnosky, I. Ferrusquia-Villafranca, R. M. Hunt, Jr., J. E. Storer, C. C. Swisher III, M. R. Voorhies, S. D. Webb, and D. P. Whistler. 2004. Mammalian biochronology of the Arikareean through Hemphillian interval (Late Oligocene through Early Pliocene epochs) p. 169-231 in M. O. Woodburne (ed. ) Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology.
This reference provides the biochronologic scheme and correlation to the radiometric and magnetostratigraphic time scales that are used in the current version of the MIOMAP archival database.
Woodburne, M. O., and C. C. Swisher, III. 1995. Land mammal high-resolution geochronology, intercontinental overland dispersals, sea level, climate, and vicariance. SEPM Special Publication 54:335-364.
This reference was used as a standard for correlations between biochronologic, magnetostratigraphic, and radiometric ages in an interim version of the MIOMAP database that existed from 2000-2003. As of 2004, all entries were adjusted to conform to Tedford et al. (2004). Prior to 2004, publications based on the then-existing MIOMAP database utilized a previously accepted standard for the late Arikareean and Early Hemingfordian