![]() ![]() ![]() Among the newly discovered fossil osteichthyans, large body size characterizes both the pycnodonts and a new freshwater Eocene catfish species, one of the largest fossil catfishes found in Africa. Building on our earlier report of the first record of rock-boring bivalves from the Paleocene of West Africa, we further describe here a Cretaceous and Paleogene mollusk fauna dominated by taxa characteristic of the modern tropics. Few macrofossil species from the Trans-Saharan Seaway show conspicuous change at either the K-Pg boundary or the PETM based on current evidence, although results are very preliminary. Our phylogenetic analyses of several vertebrate clades across the K-Pg boundary have clarified clade-by-clade species-level survivorship and range extensions for multiple taxa. We provide such a section and, consistent with prior ideas, indicate that there is a gap in sedimentation in Malian rocks in the earliest Paleocene, an unconformity also proposed elsewhere in West Africa. Our overarching goal has been to collect vertebrate fossils tied to a K-Pg stratigraphic section in Africa. The shallow marine waters included a wide range of paleoenvironments from delta systems, to hypersaline embayments, protected lagoons, and carbonate shoals. These bone beds, and the paper shales and carbonates associated with them, have preserved a diverse assemblage of fossils, including a variety of new species of invertebrates and vertebrates, rare mammals, and trace fossils. The ancient seaway left intriguing and previously unclassified phosphate deposits that, quite possibly, represent the most extensive vertebrate macrofossil bone beds known from anywhere on Earth. Ours is the first formal description of and nomenclature for the Upper Cretaceous and Lower Paleogene geological formations of this region and we tie these names to regional correlations over multiple modern territorial boundaries. We bring together and expand on our prior geological and paleontological publications and provide new information on ancient sedimentary rocks and fossils that document paleoequatorial life of the past. Northern parts of the Republic of Mali today include some of the farthest inland reaches of the ancient sea. We provide such synthesis here based on two decades of fieldwork and analyses of sedimentary deposits in the Republic of Mali. ![]() Whereas extensive epeiric seas flooded the interior portions of most continents during these intervals, the emerging multicontinental narrative has often overlooked the Trans-Saharan Seaway, in part because fundamental research, including the naming of geological formations and the primary description and analysis of fossil species, remained to be done. These species document a regional picture of ancient tropical life that spanned two major Earth events: the Cretaceous-Paleogene (K-Pg) boundary and the Paleocene-Eocene Thermal Maximum (PETM). The waters that yielded these deposits supported and preserved the remains of numerous vertebrate, invertebrate, plant, and microbial species that are now extinct. Over its approximately 50 million year episodic existence, through six major periods of transgression and regression, the Trans-Saharan Seaway left behind extensive nearshore marine sedimentary strata with abundant fossils. The edges of the sea were defined in part by the high topography of the Precambrian cratons and mobile belts of West Africa. Although it varied in size through time, the Trans-Saharan Seaway is estimated to have covered as much as 3000 km2 of the African continent and was approximately 50 m deep. ![]() Known as the Trans-Saharan Seaway, this warm and shallow ocean was a manifestation of globally elevated sea level associated with the rapid break-up of the supercontinent Gondwana in the late Mesozoic. An epicontinental sea bisected West Africa periodically from the Late Cretaceous to the early Eocene, in dramatic contrast to the current Sahara Desert that dominates the same region today. ![]()
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