Correlation of Pliocene and Pleistocene fossil assemblages from the central and eastern United States: toward a continental rodent biochronology

ABSTRACT

The ubiquitous presence and rapid evolution of rodents lend this group to the development of a correlational scheme for United States Cenozoic continental fossil deposits, equivalent to the later Cenozoic section of European MN zones. Expanding on earlier work in the Meade Basin of southwestern Kansas and Florida, Pliocene and Pleistocene mammal assemblages from the northern and southern Great Plains and the eastern United States are correlated based on rodent biostratigraphy. Eleven rodent zones (RZs) are constructed for the last 5 million years based on a new database including all rodent species assemblages during the study period. In addition to the 11 refined RZs that aid in temporal sequencing of unknown rodent assemblages, three broader biozones are recognised, including an early period characterised by the Promimomys immigration event and Hemphillian holdovers, a longer, relatively warm Pliocene to early Pleistocene period dominated by primitive cricetids and archaic arvicolids, and a final zone spanning the last two million years defined by the immigration and radiation of hypselodont Microtus and large, dentally advanced species of the cotton rat, Sigmodon. Modern rodent communities are established in the later part of Biozone 3, between about 0.6–0.3 Ma.

KEYWORDS:

• Biochronology
• biostratigraphy
• rodent
• USA

Acknowledgments

This study was made possible by many colleagues who have contributed to the inventory and chronology of North American fossil mammals. The pioneering work on paleomagnetic profiles and Cenozoic North American rodents by E. Lindsay set the scene for modern biochronology and fossil rodent phylogenetics. Seminal work in the Meade Basin by C. W. Hibbard and his students was critical for success of the Meade Basin Rodent Project, and I want to thank P. Peláez-Campomanes, D. L. Fox (and his team of geochemists), R. J. Zakrzewski, H. T. Goodwin, E. H. Lindsay, L. B. Albright, F. Marcolini, C. P. Crockett, R. Hurt, J. Baskin, W. A. Akersten, W. E. Lukens, L. Duobinis-Gray, and N. D. Opdyke, for their collaboration and contributions. The late J. Honey was instrumental in developing the modern stratigraphic framework for the Meade Basin. M. Woodburne and G. Schultz read and commented on an early version of this study.

Disclosure statement

No potential conflict of interest was reported by the author.

Supplementary material

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Additional information

Funding

This work was supported by the National Geographic Society [5963-97, 6547-99];National Science Foundation [EAR 0207582, EAR 1338262].