eserved in a fossil resin. About 70 inclusions were assignable to the genera Basilicostephanus, Coscinodiscus, Hemiaulus, Melosira, Paralia, Rhizosolenia, Skeletonema, Stephanopyxis, Trochosira, and ?Aulacoseira (some of these likely represented by several species). The diatom assemblage is mainly composed of colonial planktonic genera, which are typical for coastal shallow waters. Girard et al. find that these amber inclusions extend the fossil record of six genera from the Late Cretaceous period and support certain molecular phylogenetic assumptions regarding the diversification of marine diatoms in the Early Cretaceous period. French amber probably recorded a transition from an Early Cretaceous ancestral microflora to a more modern one. Indeed, the fossils represent a typical Late Mesozoic diatom assemblage; however, several genera are new for the Early Cretaceous period. The unusual introduction of diatom shells from beach or sea by wind, spray, or high tide onto the resin flows was possible because the amber forest grew close to the seashore.
Circulation through the Central American Seaway during the Miocene carbonate crash
Derrick R. Newkirk and Ellen E. Martin, Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA. Pages 87-90.
Tiny fossil fish teeth found in deep sea sediments record past variations in the neodymium (Nd) isotopic composition of bottom waters, which can be used to reconstruct past ocean circulation patterns. Nd data from teeth recovered from Ocean Drilling Program sites in the eastern equatorial Pacific and Caribbean Basin indicate that during the mid to late Miocene (about 16-6 million years ago), prior to closure of the Isthmus of Panama, the predominant direction of intermediate-to-deep water flow through the Central American Seaway was from the Pacific to the Atlantic. Although surface wind patterns suggest shallow flow from east to west, several General CiPage: 1 2 3 4 5 6 7 8 9 10 11 12 Related biology news :1
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