Differentiation of high-latitude and polar marine faunas in a greenhouse world

Aim The aim was to investigate those factors that influenced the differentiation of high-latitude and polar marine faunas on both ecological and evolutionary time-scales. Can a focus on a greenhouse world provide some important clues? Location World-wide, but with particular emphasis on the evolution of Antarctic marine faunas. Time period Early Cenozoic era and present day. Major taxa studied Mollusca, especially Neogastropoda. Methods The Early Cenozoic global radiation of one of the largest extant marine clades, Neogastropoda, was examined, and detailed comparisons were made between two tropical localities and Antarctica. High- to low-latitude faunal differentiation was assessed using Sørensen's dissimilarity index, and component species in each of the three faunas were assigned to 29 families and family groups. Relative diversity distributions were fitted to these three faunas and two modern ones to assess the contrast in evenness between high- and low-latitude assemblages. Results By the Middle Eocene, a distinct high-latitude neogastropod fauna had evolved in Antarctica. In addition, the distribution of species within families in this fauna is statistically significantly less even than that in the tropics. Indeed, there is no detectable difference in the scale of this separation from that seen today. Exactly as in the modern fauna, Middle Eocene Antarctic neogastropods are dominated by a small number of trophic generalist groups. Main conclusions As the hyperdiverse Neogastropoda clade radiated globally through the Early Cenozoic, it differentiated into distinct high- and low-latitude components. The fact that it did so in a greenhouse world strongly suggests that something else besides temperature was involved in this process. The predominance of generalist feeding types in the Antarctic fossil faunas is linked to the phenomenon of a seasonally pulsed food supply, exactly as it is today. Seasonality in primary productivity may act as a fundamental control on the evolution of large-scale biodiversity pattern

[Sheet No 1088] Cranz [Selenogradsk, Зеленоградск] / geological map

Geologische Karte 1: 25 000 mit Erläuterungen. Die Karte ist ein Digitalisat der Staatsbibliothek Berlin (SBB), bereitgestellt durch den Fachinformationsdienst Kartographie und Geobasisdaten (FID Karten). Das Erläuterungsheft ist ein Digitalisat des FID GEO (Fachinformationsdienst Geowissenschaften der festen Erde), erstellt durch das GDZ (Göttinger Digitalisierungszentrum), aus dem Bestand der SUB Göttingen. GeoTIFF erstellt durch FID GEO, SUB Göttingen. Koordinaten Vorlage: Nullmeridian Ferro E 038 00 - E 038 10 /N 055 00 - N 054 54.mapStaatsbibliothek Berlin (SBB), DFG, SUB Göttinge

[Sheet No 1185]; Palmnicken [Jantarny, Янтарный] / geological map

Geologische Karte 1: 25 000 mit Erläuterungen. Die Karte ist ein Digitalisat der Staatsbibliothek Berlin (SBB), bereitgestellt durch den Fachinformationsdienst Kartographie und Geobasisdaten (FID Karten). Das Erläuterungsheft ist ein Digitalisat des FID GEO (Fachinformationsdienst Geowissenschaften der festen Erde), erstellt durch das GDZ (Göttinger Digitalisierungszentrum), aus dem Bestand der SUB Göttingen. GeoTIFF erstellt durch FID GEO, SUB Göttingen. Koordinaten Vorlage: Nullmeridian Ferro E 037 30 - E 037 40 /N 054 54 - N 054 48.mapStaatsbibliothek Berlin (SBB), DFG, SUB Göttinge

Data from: The gastropod family Aporrhaidae in the Lower Cretaceous of the Neuquén Basin, west-central Argentina

The gastropod fauna of the Lower Cretaceous of the Argentinian Neuquén Basin contains three aporrhaid species. Protohemichenopus neuquensis Camacho, 1953 is the most abundant, longest-lived, and most geographically widespread of the aporrhaids of this basin, and its protoconch and early teleoconch whorls were unknown until now. The new species Dimorphosoma weaveri features convex to subtly angular spire whorls with opisthocyrt collabral ribs that are more prominent towards the mid-whorl, a bicarinate last whorl with small rounded nodes on the adapical carina, a simple, falcate labral wing which is more or less rectangular proximally and tapering and curving towards its distal end, and a short, straight rostrum. Tylostoma jaworskii Weaver, 1931 is now placed in Harpagodes, and other previous, scattered, coeval records of this genus in the basin are now recognized as part of this single species. It is believed that whereas H. jaworskii preferred shallower-water carbonate settings of low to moderate energy, P. neuquensis and D. weaveri favored siliciclastic to mixed clastic-carbonate environments, in deeper waters. In spite of its endemic elements, this aporrhaid association depicts a predominantly Tethyan influence