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The Relation of the Eocene Wilcox Flora to Some Modern Floras
Aaron J. Sharp
Vol. 5, No. 1 (Mar., 1951), pp. 1-5
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2405426
Page Count: 5
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Eighty-two (60%) of the 137 Eocene Wilcox genera known with some certainty are present in the modern flora of the southeastern United States; seventy-two genera (53%) are in the modern flora of central and eastern China; ninety-three genera (68%) are extant in the vegetation now on or near the escarpments of eastern Mexico. This high correlation with the vegetation of eastern Mexico may suggest that the Wilcox climate was similar to that of the Mexican escarpment region, which shows a mixture of temperature and tropical conditions. If some of the plant materials were not transported in Wilcox time from the pre-Ozarkian and pre-Cumberland highlands, it is possible that such genera as Fagus, Betula and Sassafras, today considered as temperate forms, had a greater ecologic amplitude then than now. Another less probable alternative is that a large number of genera have changed their ecological requirements all in the same direction since Wilcox (Lower Eocene) times.
Evolution © 1951 Society for the Study of Evolution