The Cretaceous and Paleocene pleurotomariid (Gastropoda: Vetigastropoda) fauna of Seymour Island, Antarctica

Abstract

Leptomaria antipodensis and Leptomaria hickmanae are described from the Upper Cretaceous [Maastrichtian] Lopez de Bertodano Formation, Seymour Island, and represent the first Mesozoic records of the family Pleurotomariidae from Antarctica. Leptomaria stillwelli, L. seymourensis, Conotomaria sobralensis and C. bayeri, from the Paleocene [Danian], Sobral Formation, Seymour Island, are described as new. Leptomaria larseniana (Wilckens, 1911) new combination, also from the Sobral Formation, is redescribed based on better-preserved material. The limited diversity of the pleurotomariid fauna of Seymour Island is more similar to that of the Late Cretaceous faunas of Australia and New Zealand in terms of the number of genera and species, than to the older, more diverse faunas of South America, southern India, or northwestern Madagascar, supporting the status of the Weddelian Province as a distinct biogeographic unit. The increase in the species richness of this fauna during the Danian may be due to the final fragmentation of Gondwana during this period.

The Early Origin of the Antarctic Marine Fauna and Its Evolutionary Implications

“…Within the uppermost levels of the Maastrichtian part of the López de Bertodano Formation (LBF) (Units Klb 6–9, i.e. the uppermost 450 m) there are approximately 19 genera/23 species of gastropods and 28 genera/33 species of bivalves ( [28] – [31] ; faunal list in S1 Appendix .). In addition it is apparent that within this interval bivalves are very much more abundant than gastropods, with estimates from various reference collections being in the region of 2∶1.…”

Before and after the K/Pg extinction in West Antarctica: New marine fish records from Marambio (Seymour) Island

“…The paleogeographic distribution of Notidanodon dentatus, Paraorthacodus, Protosqualus, and Edaphodon also partially agrees with the invertebrate pattern of a Boreal and an Austral Temperate Realms separated by a warmer Tethyan Realm (Kauffman, 1973;Aguirre Urreta et al, 2008). Zinsmeister (1982; see also Harasewych et al, 2009) proposed a cold temperate Weddellian marine mollusk province for the shallow seas ranging from southern South America through Antarctica to Australia and New Zealand. Later, it was extended to land faunas and floras as well (see Reguero et al, 2013).…”