The historical reconstruction of the origin and dispersal of plant taxa in space and time facilitates a better understanding of theirmodern distribution patterns. However,most studies of paleobiogeography have focused on terrestrial plants, and the distribution changes of aquatic plants are less well understood. Here we study the lotus plant Nelumbo (Nelumbonaceae), an aquatic perennial herb, with a disjunctive distribution across East, South and Southeast Asia-North Australia and North America. The reproductive organs of Nelumbo changchangensis He et Jin from the Eocene of Hainan, China are supplementarily described. Analysis of the spatial and temporal distributions of Nelumbo in the geologic past indicates that the genus first occurs in mid-latitude area of Laurasia in the Early Cretaceous, then becomeswidespread in North America and Eurasia and expands into SouthAmerica during the Late Cretaceous, and reaches its maximum northern limit during the Eocene. The genus persists and thrives in North America and Eurasia until the Pliocene. The Pleistocene ice age causes the extinction of Nelumbo in Europe and central Asia, and its populations in North American and Asia are also restricted to refuges of lower latitude. Like the terrestrial plants Metasequoia (Cupressaceae) and Nordenskioeldia (Trochodendraceae), the fluctuations of Nelumbo distribution ranges are also linked to climatic changes in the Cenozoic. The cooling climate and increasing seasonality in the Eocene of East Asia may favor the origin of tubers and the differentiating of the ecotypes in lotus, which allow the deciduous type to survive in cold winters.
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RBINS Staff Publications
Numerous bird bones from the Paleocene and early Eocene of the Belgian and Paris basins have been collected by amateur paleontologists. Four bones from the early-middle Selandian of Maret, Belgium are among the earliest Cenozoic avian remains from Europe and include the oldest temporally well constrained records of the Gastornithidae, as well as tentative records of the paleognathous Lithornithidae and the Ralloidea. Another assemblage from the middle Thanetian of Templeuve, France contains multiple bones of the Lithornithidae as well as a record of the Pelagornithidae. Specimens from the latest Thanetian of Rivecourt-Petit Pâtis, France are tentatively assigned to the Ralloidea and Leptosomiformes. An assemblage of 54 bones from the middle Ypresian of Egem, Belgium represents at least 20 species in more than 11 higher-level taxa. Well-identifiable specimens are assigned to the Odontopterygiformes, Galliformes, Messelornithidae, Apodiformes, Halcyornithidae, Leptosomiformes, and Coraciiformes. Further specimens are tentatively referred to the phaethontiform Prophaethontidae and to the Accipitridae, Masillaraptoridae, and Alcediniformes. These three-dimensionally preserved fossils provide new data on the osteology of taxa that are otherwise mainly known from compression fossils with crushed bones. They also further knowledge of the composition of early Paleogene avifaunas of the North Sea Basin. Paleocene avifaunas of Europe and North America appear to have had different compositions and only a few taxa, such as the paleognathous Lithornithidae, are known from both continents. This suggests that the very similar early Eocene avifaunas of Europe and North America are the result of early Cenozoic dispersal events. The well-represented small galliform species from Egem most closely resembles Argillipes aurorum, an ignored galliform species from the London Clay. The tentatively identified fossils of Accipitridae and Alcediniformes would represent the earliest fossil records of these clades. The birds from Egem include few seabirds (Odontopterygiformes, cf. Prophaethontidae) and is dominated by terrestrial species (Galliformes, Messelornithidae). Arboreal birds (Halcyornithidae, Leptosomiformes, cf. Alcediniformes, Coraciiformes) are less abundant and aerial insectivores (Apodiformes) very scarce, which either indicates a taphonomic bias in the composition of the avifauna or particular paleoenvironmental characteristics of the nearshore habitats in that area of the southern North Sea Basin. Grant Information: Funded by Belgian Science Policy Office (project BR/121/A3/PalEurAfrica).
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RBINS Staff Publications 2019
