Revision of the eocene flora of southeastern north America.

Authors

  • D.L. Dilcher Department of Botany, Indiana University, Bloomington, Indiana, U.S.A.

DOI:

https://doi.org/10.54991/jop.1971.882

Abstract

The Lower Eocene floras of southeastern North America were first published as a comprehensive flora by E. W. Berry in 1916 and later revised by him in 1930. This flora is one of the largest and most completely studied Eocene floras in North America. However, reinvestigation, presently in progress, has resulted in several revisions. Improved methods of research, more detailed and inclusive study expanding into new areas of research, and the increased understanding that has resulted from continued study in previously established areas of research, as well as the recent remapping of important deposits and the continued collection of fossil material, have provided the tools and information necessary for this revision. The age of these deposits has been revised from Wilcox group (Lower Eocene) to Claiborne group (Middle Eocene) and the nature of the deposits may now best be considered to be leaf-bearing clays laid down in ancient oxbow lakes. Recent studies of the cuticular remains of some leaves and pollen indicate that the clay pits are not isochronous but span the range of time of the Middle Eocene.

Work which has been completed indicates that at least 60% of the taxonomic relationships of fossil forms to modern families and genera published by Berry are incorrect.

When the fine venation and cuticular remains of the leaves are examined the presence of several extant taxa which Berry reported cannot be substantiated. Some taxonomic revisions are proposed; some of the fossil leaves studied could not be assigned to any known taxa and may represent extinct forms. The evolution of the angiosperms in the early Tertiary is often misunderstood because of the excessive number of extant generic and family names that are applied to fossil leaves with little or no detailed analysis of the fine venation or cuticular features of either modern or fossil angiosperms.

The use of taxonomic affinities, community structure, and foliar physiognomy in making palaeoecological interpretations of early Tertiary floras is mentioned and the climate during Middle Eocene time in western Kentucky and Tennessee is reevaluated. The climate appears to have been dryer and somewhat cooler than previous investigators indicated.

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Published

1971-12-31

How to Cite

Dilcher, D. (1971). Revision of the eocene flora of southeastern north America. Journal of Palaeosciences, 20(1-3), 7–18. https://doi.org/10.54991/jop.1971.882

Issue

Section

Research Articles