The early Paleogene is critical for understanding global biodiversity patterns in modern ecosystems. During this interval, Southern Hemisphere continents were largely characterized by isolation and faunal endemism following the breakup of Gondwana. Africa has been proposed as an important source area for the origin of several marine vertebrate groups but its Paleogene record is poorly sampled, especially from sub-Saharan Africa. To document the early Paleogene marine ecosystems of Central Africa, we revised the stratigraphic context of sedimentary deposits from three fossil-rich vertebrate localities: the Landana section in the Cabinda exclave (Angola), and the Manzadi and Bololo localities in western Democratic Republic of Congo. We provide more refined age constraints for these three localities based on invertebrate and vertebrate faunas, foraminiferal and dinoflagellate cyst assemblages, and carbon isotope records. We find an almost complete absence of Danian-aged rocks in the Landana section, contrary to prevailing interpretations over the last half a century (only the layer 1, at the base of the section, seems to be Danian). Refining the age of these Paleocene layers is crucial for analyzing fish evolution in a global framework, with implications for the early appearance of Scombridae (tunas and mackerels) and Tetraodontiformes (puffer fishes). The combination of vertebrate fossil records from Manzadi and Landana sections suggests important environmental changes around the K/Pg transition characterized by an important modification of the ichthyofauna. A small faunal shift may have occurred during the Selandian. More dramatic is the distinct decrease in overall richness that lasts from the Selandian to the Ypresian. The Lutetian ofWest Central Africa is characterized by the first appearance of numerous cartilaginous and bony fishes. Our analysis of the ichthyofauna moreover indicates two periods of faunal exchanges: one during the Paleocene, where Central Africa appears to have been a source for the European marine fauna, and another during the Eocene when Europe was the source of the Central Africa fauna. These data indicate that Central Africa has had connections with the Tethyian realm.
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Saniwa is an extinct genus of varanid lizard from the Eocene of North America and Europe. It is the sister taxon to the crown-group Varanus. Up to now, only one poorly known species is recognized from Europe, Saniwa orsmaelensis from the earliest Eocene of Dormaal, Belgium. This species originally named by Louis Dollo nearly a century ago, is the earliest varanid of Europe. Unfortunately, the material was limited to vertebrae with only preliminary description and no figure provided, except for one dorsal vertebra that later has been designated as the lectotype. Here we describe and illustrate new fossil specimens collected from Dormaal and other early Eocene localities of the Paris Basin, France, including dentary and maxilla fragments as well as skull material, allowing to reassess the validity of the European taxon. These fossils allow further comparisons with the type-species, Saniwa ensidens, from the late early Eocene Bridger and Green River formations of Wyoming and to propose a new diagnosis for S. orsmaelensis. The occurrence of S. orsmaelensis is restricted to the early Eocene of Northwest Europe and its geographic origin is unresolved because the earliest record of Saniwa in North America is also from the earliest Eocene. The brief presence of varanid lizards in the European Paleogene could result from two major climatic events. At the Paleocene Eocene Thermal Maximum, large biotic interchanges occurred in the northern hemisphere allowing new dispersals into Europe. However, at the end of the Eocene, thermophilic lizards disappeared due to cooler conditions. Another hypothesis for their disappearance could be the competition that occurred with other anguimorph lizards. Grant Information: This abstract is a contribution to the Belspo Brain network project BR/121/A3/PalEurAfrica funded by the Belgian Science Policy Office.
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