scholarly journals The molluscs of the “Falunière” of Grignon (Middle Lutetian, Yvelines, France): quantification of lithification bias and its impact on the biodiversity assessment of the Middle Eocene of Western Europe

Geodiversitas ◽  
2015 ◽  
Vol 37 (3) ◽  
pp. 345-365 ◽  
Author(s):  
Malcolm T. Sanders ◽  
Didier Merle ◽  
Loïc Villier
Keyword(s):  
Western Europe ◽  
Middle Eocene ◽  
Biodiversity Assessment

scholarly journals New fossils of Sirenia from the Middle Eocene of Navarre (Western Pyrenees): the oldest West European sea cow record

2010 ◽  
Vol 147 (5) ◽  
pp. 665-673 ◽  
Author(s):  
H. ASTIBIA ◽  
N. BARDET ◽  
X. PEREDA-SUBERBIOLA ◽  
A. PAYROS ◽  
V. DE BUFFRÉNIL ◽  
...  
Keyword(s):  
Western Europe ◽  
Middle Eocene ◽  
Histological Study ◽  
Regional Stage ◽  
Postcranial Remains ◽  
Sea Cow ◽  
Western Pyrenees ◽  
West European

AbstractPostcranial remains of Sirenia from the early Middle Eocene (late Lutetian) Urbasa-Andia Formation of Navarre (Western Pyrenees) are described. The material consists of two partial atlas vertebrae, one humerus and several dorsal ribs (from Arrasate, Urbasa plateau), and partial dorsal ribs (from Lezaun, Andia plateau). The morphology of the fossils is consistent with referral to Dugongidae, the only sirenian clade known so far in the Middle Eocene of Europe. Moreover, the histological study of the ribs shows that the pachyosteosclerosis of extant Sirenia was definitively present by the early Middle Eocene. The oldest sirenian remains reported to date in the Pyrenean Realm were assigned to the Biarritzian, a regional stage that is currently ascribed either to the middle or to the lower–middle Bartonian. Therefore, the sirenian remains of Lezaun, reliably dated as late Lutetian (SBZ16 zone) in age, are definitively the earliest sirenian fossils known in Western Europe and are among the oldest sea cow records of Europe.

scholarly journals Differing histories of Eocene angiosperm diversity in eastern North America and western Europe: dependence on paleogeography

1992 ◽  
Vol 6 ◽  
pp. 105-105
Author(s):  
Norman O. Frederiksen
Keyword(s):  
North America ◽  
Western Europe ◽  
Environmental Heterogeneity ◽  
Gulf Coast ◽  
Middle Eocene ◽  
Late Eocene ◽  
Middle Part ◽  
Eastern North America ◽  
Climatic Fluctuations ◽  
Angiosperm Pollen

Studies of Eocene angiosperm pollen floras in eastern North America (my work, especially in the eastern Gulf Coast) and western Europe (Boulter, Krutzsch) have shown significant differences in floral diversities between the two regions: in western Europe, maximum diversity was in the early Eocene and it decreased thereafter, in eastern North America, maximum diversity was in the middle part of the middle Eocene. The hypothesis presented here is that paleogeography was an important control on the diversity histories in the two regions: eastern North America was part of a large terrestrial landmass, whereas the terrestrial depositional basins of western Europe were on islands or peninsulas surrounded by the sea. Migrations between eastern and western North America were relatively easy, but migrations within what is now western Europe involved island-hopping, which explains distinct diachroneity of some angiosperm first appearances among different basins there. Western European basins were in contact with a large land mass during late Paleocene time but became isolated and smaller during the middle to late Eocene marine transgression. These changes resulted in decreased genetic exchange and increased probabilities of extinction due to (1) greater competition among species because of a reduced number of niches and (2) presence of small, isolated species populations, leading to local variations in extinctions, which probably explain the observed diachronism of taxon last appearances in different areas of Europe. Terrestrial climatic cooling in western Europe may be linked to decreasing contact between the NW European Tertiary Basin and the warm Tethys Seaway during the middle and late Eocene. In short, some combination of low environmental heterogeneity, geographic isolation, and long-term climatic deterioration probably caused the decrease in angiosperm diversity during the middle and late Eocene in western Europe.Several factors encouraged increasing or stable diversity in eastern North America but were far less effective in western Europe: (1) Eastern North America underwent greater climatic fluctuations during the Eocene (thus, immigration of taxa with different climatic preferences took place at different times), whereas the islands and peninsulas of western Europe had more uniform, maritime climates. (2) Evolution and immigration of r-selected taxa in eastern North America were favored by distinct dry seasons at certain times during the Eocene and by repeated marine transgressions and regressions that created opportunities for evolution and immigration of r-selected plants on and to freshly exposed coastal plain. In contrast, the predominantly maritime climates of western Europe in the early and middle Eocene favored K-selected plants, which had fewer possibilities for evolution and which had greater difficulty in migrating because island-hopping taxa are mainly r-selected. (3) “Arcto-Tertiary” taxa adapted to cooler climates lived and evolved in the uplands of the Appalachian Mountains, whereas western Europe was relatively flat in the Eocene –another example of its relative lack of environmental heterogeneity.

Quaternary colonization or Paleogene persistence?: historical biogeography of skates (Chondrichthyes: Rajidae) in the Antarctic ichthyofauna

Paleobiology ◽  
1994 ◽  
Vol 20 (2) ◽  
pp. 215-228 ◽  
Author(s):  
Douglas J. Long
Keyword(s):  
Western Europe ◽  
Middle Eocene ◽  
Habitat Preferences ◽  
Drake Passage ◽  
The Arctic ◽  
Western Atlantic ◽  
Western Tethys ◽  
Antarctic Waters ◽  
La Meseta Formation ◽  
Dispersal Corridor

Seven endemic species of skates (Chondrichthyes: Rajidae) represent the only family of elasmobranchs currently known to live in Antarctic continental waters. Many previous authors believed skates colonized Antarctic waters from Patagonia during interglacial periods in the Quaternary. However, recent fossil material collected from the middle Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula, indicates that they may have persisted in Antarctic waters since the Paleogene. Additionally, oceanographic barriers present in the Neogene and Quaternary would have prevented dispersal from southern continents to Antarctica. A revised dispersal scenario, based on skate fossils, biology, paleogeography, and present centers of skate diversity, suggests that skates evolved in the western Tethys and North Boreal seas of western Europe in the Late Cretaceous and early Paleogene and emigrated into Antarctica during the early to middle Eocene via a dispersal corridor along the continental margins of the western Atlantic Ocean. Skates probably populated the Pacific Basin by passing from this dispersal corridor through the Arctic Ocean. Vicariant events, such as opening of the Drake Passage, the development of the Circum-Antarctic Current, and formation of deep and wide basins around Antarctica in the late Paleogene, created barriers that isolated some species of skates in Antarctica and prevented movement of other species of skates into Antarctica from northern areas. Skates are the only group of fishes known to have survived the Oligocene cooling of Antarctica that killed or extirpated the Paleogene ichthyofauna; they persisted by a combination of cold-tolerance, generalized diet, and unspecialized bathymetric and habitat preferences.

scholarly journals Tarsal morphology of ischyromyid rodents from the middle Eocene of China gives an insight into the group’s diversity in Central Asia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Łucja Fostowicz-Frelik ◽  
Sergi López-Torres ◽  
Qian Li
Keyword(s):  
North America ◽  
Western Europe ◽  
Middle Eocene ◽  
Northern China ◽  
Taxonomic Diversity ◽  
Late Eocene ◽  
Modern Aspect ◽  
Tarsal Bones ◽  
Mammal Assemblages ◽  
First Time

AbstractIschyromyids are a group of large rodents with the earliest fossil record known from the late Paleocene (Clarkforkian) of North America; they are considered the earliest fossil representatives of Rodentia of modern aspect. Ischyromyids dominated early Paleogene small-mammal assemblages of North America and in the latest Paleocene migrated to western Europe and to Asia; in the latter they survived only to the beginning of the late Eocene, but were never abundant. Here we describe for the first time the calcanei of ischyromyids from the early middle Eocene of the Erlian Basin in Nei Mongol, northern China. These calcanei document the existence of three species. The morphology of the studied tarsal bones overall suggests ambulatory locomotion for these animals (‘slow cursors’), similar to that of the coypu and porcupines, but one form shows more marked cursorial capabilities. These differences show that Chinese ischyromyids, although rare, had attained greater taxonomic diversity by the middle Eocene in Nei Mongol than estimated from dental remains. We also address the question of the morphological and ecological divergence of these ischyromyids in relation to their North American counterparts, as well as the issue of a direct dispersal route from North America to Asia in the early Eocene.

West coast North America record of the Paleogene marine stromboid gastropodRimellaand paleobiogeography of the genus

2013 ◽  
Vol 87 (5) ◽  
pp. 826-841 ◽  
Author(s):  
Richard L. Squires
Keyword(s):  
North America ◽  
West Coast ◽  
Western Europe ◽  
Middle Eocene ◽  
Late Eocene ◽  
New Combination ◽  
The West ◽  
Early Oligocene ◽  
Early Paleocene ◽  
First Time

The west coast of North America record of the shallow-marine stromboid gastropod genusRimellaAgassiz, 1841 is restudied for the first time in 90 years. This genus comprises a small group of Paleogene gastropods characterized by having an ornamented fusiform shell, a posterior canal ascending the spire, and simple (non-flared) outer lip.Rimella, whose familial ranking has been inconsistent, is placed here in family Rostellariidae Gabb, 1868, subfamily Rimellinae Stewart, 1927.EctinochilusCossmann, 1889;MacilentosClark and Palmer, 1923;VaderosClark and Palmer, 1923; andCowlitziaClark and Palmer, 1923 are recognized here as junior synonyms ofRimella. Four species are recognized from the west coast of North America: early to middle EoceneRimella macilentaWhite, 1889; early EoceneRimella oregonensisTurner, 1938; middle to late EoceneRimella supraplicata(Gabb, 1864) new combination, of whichRostellaria canaliferGabb, 1864,Cowlitizia washingtonensisClark and Palmer, 1923, andCowlitzia problematicaHanna, 1927 are recognized here as junior synonyms; and late EoceneRimella elongataWeaver, 1912.Rimellawas a warm-water gastropod whose earliest known record is of early Paleocene (Danian) age in Pakistan. Other than the west coast of North America,Rimellais found in Eocene strata in western Europe, Turkey, Egypt, Pakistan, southeastern United States, Panama, Peru, and, to a lesser degree, in Trinidad, Columbia, Java, and New Zealand. Global cooling near the end of the Eocene greatly diminished the genus. Its youngest known occurrences are of early Oligocene age in Germany, Italy, England, and Peru.

scholarly journals The Eocene flora of Tatabánya “marl-mine” (N Hungary)

2020 ◽  
Vol 100 (3) ◽  
pp. 629-645 ◽  
Author(s):  
Boglárka Erdei ◽  
Volker Wilde
Keyword(s):  
Western Europe ◽  
Middle Eocene ◽  
Southeastern Europe ◽  
Fossil Plant ◽  
Plant Assemblage ◽  
Plant Remains ◽  
Entire Margin ◽  
Central And Southeastern Europe

Abstract The middle Eocene (Lutetian) fossil plant assemblage from Tatabánya (N Hungary) comprises plant remains preserved mostly as impressions. Remains of angiosperms are represented by Lauraceae (Laurophyllum div. sp., Daphnogene Unger), Rhamnaceae (Ziziphus Miller), Malvaceae s.l. (Byttneriopsis Z.Kvaček et Wilde), Leguminosae, and Palmae, and the occurrence of other families, i.e., Dioscoreaceae, Myrtaceae, Fagaceae, Anacardiaceae, Berberidaceae, Juglandaceae, and Theaceae, is uncertain. The scarcity of gymnosperms is a character similar to the coeval floras of Csordakút (N Hungary) and Girbou in Romania. The presence of Ziziphus ziziphoides (Unger) Weyland, high number of linear shaped leaves with entire margin and coriaceous texture (Lauraceae vel Fagaceae), and small-leaved Leguminosae suggests a “subhumid” character of the vegetation, which is recognisable also in early Palaeogene floras of eastern Central and Southeastern Europe, e.g., the Tard Clay floras in Hungary and floras of Serbia/Macedonia. In contrast, the Eocene floras from Central/Western Europe are indicative of a generally non-xerophytic character, e.g., Staré Sedlo in Bohemia, Messel, Geiseltal, and the Weisselster Basin floras in Germany. A frost-free climate with high mean annual temperatures similar to that estimated for coeval European floras may also be inferred for the Tatabánya flora.

The geology of the western approaches of the English Channel. I. Chalky rocks from the upper reaches of the continental slope

1962 ◽  
Vol 245 (724) ◽  
pp. 267-290 ◽  
Keyword(s):  
Continental Shelf ◽  
Continental Slope ◽  
Western Europe ◽  
Middle Eocene ◽  
English Channel ◽  
Geological Time ◽  
Structural Explanation ◽  
Upper Miocene ◽  
Clastic Sediment

Dredged samples of Tertiary chalks are described from five stations distributed over a distance of about 200 miles along the continental slope. The Foraminifera and nannoplankton indicate a range in age from Middle Eocene to Upper Miocene. The conclusions are reached that (i), the continental slope appears not to have received and retained much clastic sediment of recent geological time, (ii), the facies of the chalks is quite different from that recorded in western Europe, (iii), the chalks crop out at least in the upper reaches of the slope and form terraces, (iv), a structural explanation, probably faulting, is required to account for the conflicting topographical and stratigraphical levels of some samples and (v), there is no support for the existence before Pleistocene times of the continental shelf of the Western Approaches in physiographical form similar to that known today.

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