Newly discovered remains of the early Middle Eocene (Lutetian) sirenian Protosiren (Protosirenidae) in shark tooth rich conglomerates from a coastal delta environment northwest of the European Rhenish Massif at Fü...Newly discovered remains of the early Middle Eocene (Lutetian) sirenian Protosiren (Protosirenidae) in shark tooth rich conglomerates from a coastal delta environment northwest of the European Rhenish Massif at Fürstenau (northwestern Germany), represent the most northerly occurrence of this genus whose global distribution was generally restricted to warm waters. Its presence of the remains so far north can be explained by seasonal inflow of warm Tethys surface water into the cool, upwelling-influenced, basin. The existence of two discrete centers of sirenian evolution can be explained by the opening of the Atlantic and the upwelling that separated the North American warm water faunal province from those of Africa and Eurasia. A slightly modified evolutionary model is presented in which the oldest Early Eocene manatee sirenians evolved in the Caribbean of Central America. Protosiren, however, appears to have developed polyphyletically along the African coastline of the Tethys, and represents the oldest known dugong ancestor. Younger (Oligocene) European sirenian skeletons of Halitherium and Anomotherium are included in the phylostratigraphic model in which sirenians had generally reduced their teeth by 28 Ma as an adaptation for feeding on sea-plants (macroalgae/seagrass). Teeth from early megatooth sharks, which preyed on sirenians, have been recorded from shallow marine Eocene and Oligocene coastlines of the southern proto-North Sea Basin, and shark bite marks have been found on sirenian skeletons.展开更多
The early white shark Carcharodon Smith, 1838 with the fossil Carcharodon auriculatus (Blainville, 1818) and the extinct megatooth shark Otodus Agassiz, 1843 with species Otodus sokolovi (Jaeckel, 1895) were both pres...The early white shark Carcharodon Smith, 1838 with the fossil Carcharodon auriculatus (Blainville, 1818) and the extinct megatooth shark Otodus Agassiz, 1843 with species Otodus sokolovi (Jaeckel, 1895) were both present in the European proto North Sea Basin about 47.8 - 41.3 m.y. ago (Lutetian, early Middle Eocene), as well as in the Tethys realm around the Afican-Eurasian shallow marine habitats. Both top predators developed to be polyphyletic, with possible two different lamnid shark ancestors within the Early Paleocene to Early Eocene timespan with Carcharodon (white shark line-age) and Otodus (megatooth shark lineage). Their sawblade teeth developed during the early Paleogene as the result of adaptation to feeding on various marine new rising mammals, coinciding with three main waves of evolutionary emergence of seals, sirenians, and whales in parallel with the evolution of these large predatory sharks. Megatooth sharks specialized in hunting whales and sirenians only on the coastal shelves of warm oceans and disappeared globally in the Pleistocene due to climate change and ocean cooling. The cold-water adapted early white sharks have survived until the present day with body temperate change adaptation in warm to temperate oceans and are proposed to have specialized on coastal seal hunting already50 m.y. ago.展开更多
In the greenhouse world of the Early UpperCretaceous of Europe giant cephalopod shells of thehemibenthic ammonite Puzosia formed hugeaccumulations.Their shells indicate adaptations in thebody chamber morphology depend...In the greenhouse world of the Early UpperCretaceous of Europe giant cephalopod shells of thehemibenthic ammonite Puzosia formed hugeaccumulations.Their shells indicate adaptations in thebody chamber morphology depending on theenvironment.On the sea floor,deposited ammonite shellsscoured up to 50 cm depth which caught more and morelarge shells over extended periods of time.They built upto five square meter extended scour troughs in which theshells are enriched in chain-,fan-and fan layer orderswith a maximum accumulation of 24 cephalopods.Between these hundreds of other macrofaunal remainsaccumulated.The ammonite shells were benthic islandsand minibiotopes in carbonate soft-to firm groundenvironments along a submarine swell in the southernNorth Sea Basin of Central Europe.The empty shellsencrusted by different epizoans sheltered and protectedalso crustaceans,which undermined the empty shells bybioturbation.Small and extremely rare squamate reptilesof the marine Dolichosaurus longicollis possibly tookshelter or fed within these unique benthic submarinedepression“islands”.展开更多
文摘Newly discovered remains of the early Middle Eocene (Lutetian) sirenian Protosiren (Protosirenidae) in shark tooth rich conglomerates from a coastal delta environment northwest of the European Rhenish Massif at Fürstenau (northwestern Germany), represent the most northerly occurrence of this genus whose global distribution was generally restricted to warm waters. Its presence of the remains so far north can be explained by seasonal inflow of warm Tethys surface water into the cool, upwelling-influenced, basin. The existence of two discrete centers of sirenian evolution can be explained by the opening of the Atlantic and the upwelling that separated the North American warm water faunal province from those of Africa and Eurasia. A slightly modified evolutionary model is presented in which the oldest Early Eocene manatee sirenians evolved in the Caribbean of Central America. Protosiren, however, appears to have developed polyphyletically along the African coastline of the Tethys, and represents the oldest known dugong ancestor. Younger (Oligocene) European sirenian skeletons of Halitherium and Anomotherium are included in the phylostratigraphic model in which sirenians had generally reduced their teeth by 28 Ma as an adaptation for feeding on sea-plants (macroalgae/seagrass). Teeth from early megatooth sharks, which preyed on sirenians, have been recorded from shallow marine Eocene and Oligocene coastlines of the southern proto-North Sea Basin, and shark bite marks have been found on sirenian skeletons.
文摘The early white shark Carcharodon Smith, 1838 with the fossil Carcharodon auriculatus (Blainville, 1818) and the extinct megatooth shark Otodus Agassiz, 1843 with species Otodus sokolovi (Jaeckel, 1895) were both present in the European proto North Sea Basin about 47.8 - 41.3 m.y. ago (Lutetian, early Middle Eocene), as well as in the Tethys realm around the Afican-Eurasian shallow marine habitats. Both top predators developed to be polyphyletic, with possible two different lamnid shark ancestors within the Early Paleocene to Early Eocene timespan with Carcharodon (white shark line-age) and Otodus (megatooth shark lineage). Their sawblade teeth developed during the early Paleogene as the result of adaptation to feeding on various marine new rising mammals, coinciding with three main waves of evolutionary emergence of seals, sirenians, and whales in parallel with the evolution of these large predatory sharks. Megatooth sharks specialized in hunting whales and sirenians only on the coastal shelves of warm oceans and disappeared globally in the Pleistocene due to climate change and ocean cooling. The cold-water adapted early white sharks have survived until the present day with body temperate change adaptation in warm to temperate oceans and are proposed to have specialized on coastal seal hunting already50 m.y. ago.
基金supported by grants, between 1994-2001,from the Deutsche Forschungsgesellschaft (DFG Str.98/3)the LandNorth-Rhine Westphalia (City Halle/Westph.)+2 种基金the LandkreisOsnabrück, the Bezirksregierung Detmold, the NaturparkvereinNördlicher Teutoburger Wald-Wiehengebirge e.V.the HeimatvereinBorgholzhausen e. V.the Naturkundemuseum Bielefeld.
文摘In the greenhouse world of the Early UpperCretaceous of Europe giant cephalopod shells of thehemibenthic ammonite Puzosia formed hugeaccumulations.Their shells indicate adaptations in thebody chamber morphology depending on theenvironment.On the sea floor,deposited ammonite shellsscoured up to 50 cm depth which caught more and morelarge shells over extended periods of time.They built upto five square meter extended scour troughs in which theshells are enriched in chain-,fan-and fan layer orderswith a maximum accumulation of 24 cephalopods.Between these hundreds of other macrofaunal remainsaccumulated.The ammonite shells were benthic islandsand minibiotopes in carbonate soft-to firm groundenvironments along a submarine swell in the southernNorth Sea Basin of Central Europe.The empty shellsencrusted by different epizoans sheltered and protectedalso crustaceans,which undermined the empty shells bybioturbation.Small and extremely rare squamate reptilesof the marine Dolichosaurus longicollis possibly tookshelter or fed within these unique benthic submarinedepression“islands”.
