Plant Microfossils and Age of Nonmarine Cretaceous Sediments of Maryland and Delaware

A preliminary report on the pollen and spores of the pre-Selma Upper Cretaceous strata of western Alabama

“…By comparison, the average of 39 and 38 percent of dicots in the Tuscaloosa and McShan-Eutaw :floras, respectively, is higher than percent of dicots for the Potomac group as observed by Groot and Penny (1960) and significantly lower than their percentage in the available USGS n1aterial from the Magothy forn1ation.…”

“…That these floras are younger than the parts of the Potomac group as reported by Groot and Penny (1960) is shown by the relatively higher cmnpositional percentages of dicots, and by the more advanced n1orphology of the dicot forms represented in the pre-Selma floras. The unpublished data of Steeves concerning the Raritan pollen flora is permissive evidence for the correlation of the upper part of the Raritan formation with the Coker formation, as suggested by Stephenson and others (1942).…”

“…In a recent summary of the pollen :floras in the Potomac group of Cretaceous age in the eastern United States, Groot and Penny (1960) stated that dicot pollen represent less than 28 percent of pollen and spore tallies within those strata. In table 18, the range of percentages for the Raritan formation and older Cretaceous strata are listed, along with a tally from USGS collections from the type section of the Magothy formation; ages of the forn1ations are listed according to Dorf (1952) and the Stephenson committee (Stephenson and others, 1942).…”

“…In a recent evaluation of evidence concerning the evolutionary rise of the angiosperms, Scott, Barghoorn, and Leopold (1960) concluded that many of the pre-Cretaceous fossil "angiosperms" are of questionable affinities, that the preponderant clear evidence of early angiosperms indicates that they first appear in the fossil record in (table 18), Groot and Penny (1960) recorded as much as 21 percent angiosperm pollen, but, because they recognized that some of their data were at variance with those from other N eocomian material, they concluded that the angiosperm-rich material very probably is younger than N eocomian (Groot and Penny, 1960, p. 228). Pollen and spore tallies are not available from European Cenomanian through Coniacian and Senonian strata but floral lists indicate that the first striking increase in dicot species occurs in the Turonian (Krutzsch, 1957).…”

“…About half of the 20 forms that Groot and Penny (1960) described from the Potomac group also are represented in the pre-Selma floras. Most of the dicots described by Groot and Penny are of simple, primitive morphology, being mainly of tricolpate and tricolporoid structure.…”