LATE CRETACEOUS EQUATORIAL COASTAL VEGETATION: NEW MEGAFLORA ASSOCIATED WITH DINOSAUR FINDS IN THE BAHARIYA OASIS, EGYPT

Paleoequatorial forests are not well known from the Cretaceous, but recent excavations associated with dinosaur finds in the Bahariya Oasis (Western Desert, Egypt) have revealed several fossil plant localities that shed light on such environments. The Cenomanian (early Late Cretaceous) Bahariya Formation, a transgressive sequence of the Tethys shoreline, consists of coastal deposits near the base and more marine sediments higher in the section. Plant remains, including leaf impressions and infructescences, were found in lagoonal and intertidal deposits. Some localities have very sparse plant remains, suggesting long transport from inland forests, while other localities contain numerous complete compound leaves, indicating very little transport. Freshwater taxa, such as Nelumbites and floating aquatic ferns, are found in saltwater-influenced sedimentary environments (indicated by such features as flaser bedding). This suggests that freshwater ponds existed in the paralic environment. The megaflora contains approximately 30 morphotypes, of which ~25 are angiosperms. Members include ferns such as Cladophlebis, aff. Marsilea, and Weichselia reticulata; gymnosperms such as Agathis; and a number of dicots such as Nelumbites, Liriodendrites, and others with affinities to Lauraceae, Platanaceae, Sapindales, and Piperaceae?. The form genera are similar to those found in North American Cenomanian megafloras, such as the Dakota Group Flora (also found in coastal deposits). Because North Africa was separated from North America and Eurasia by both the Tethys Sea and the widening Atlantic Ocean in the Cenomanian, shared leaf forms pose interesting biogeographical questions. Preliminary examinations of leaf physiognomy suggest that the flora contains a relatively high number of entire-margined forms and that the leaves are relatively small. This suggests that this area was relatively dry and warm in the Cenomanian. Similarities in leaf physiognomy between this low latitude flora and other Cenomanian floras in middle latitudes suggest that climate gradients were less pronounced in the early Late Cretaceous.