Fig 15-16 - uploaded by Ronald Pouwer
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Nassarius elegans ( J. de C. Sowerby, 1824). Overloop van Hansweert (strand Baarland); leg. R. Rijken; (15) H. 11 mm.; (16) H. 15 mm.
Citations
... its species name). Norton (1975) and Spaink (Gladenkov et al., 1980) refer this species to the genus Nassarius Duméril, 1806, and we will follow them, also with the other species of Nassaridae found in the Tjörnes beds (see furthermore Rijken and Pouwer (2014)). ...
Systematic overview of the molluscan and barnacle assemblages of the Pliocene Tjörnes sequence in North Iceland is primarily based on collections and fieldwork carried out during the last 50 years and collections of the Institute of Natural History in Reykjavík, the Geological Museum in Copenhagen, and the collection of the late farmer Jóhannes Björnsson in Ytri-Tunga on Tjörnes. We have identified 65 species of prosobranch gastropods, five opistobranch gastropod, 49 bivalve, one ammonite, and one barnacle species. Of the 119 molluscan species, 24 have not been recorded before from Tjörnes. About 25% of the mollusc species are extinct, and 25 of the recent molluscan species now live in southerly localities with higher sea temperatures. At least 32 of the species have their first appearance (FAD) in Tjörnes. The species are depicted on plates and variation in shape is demonstrated wherever possible. The distribution, recent or fossil, of species is shown, and ecological and biological features discussed. The larval development of the species is also summarized. The Tjörnes fauna is major record of trans-Arctic oceanic interchange that has been imperative in shaping the modern North Atlantic faunas. This review enables us to improve our understanding of the interchange.
... We are uncertain about the taxonomic status of Pussilina radiata balkeii, which is the subject of further study. Tritia reticulata s.l. may include the similar T. nitida because these species can only be reliably identified on adult material, hence their grouping (Rijken & Pouwer, 2014). The same applies to Stagnicola palustris s.l., for which several species are known that are difficult or impossible to distinguish on limited shell characteristics. ...
When dealing with stratigraphic successions in marginal basin settings, the geological record is often fragmented due to erosion and reworking processes. The North Sea Basin is an example: it has a fragmented Quaternary record; in particular, Middle Pleistocene intervals are poorly known. As a result, we have little insight into climate, marine environmental conditions and biodiversity in this period. Here we describe and discuss a succession of three interglacial marine mollusc-bearing intervals in a borehole from Ameland in the northern Netherlands (borehole B01H0189 near Hollum). These intervals are attributed to marine isotope stages MIS7, MIS5e and MIS1. The Holocene Celtic type of faunas (interval 0–26.24 m below surface (b.s.)) and Eemian Lusitanian type of faunas (26.24–30.40 m b.s.) are well-known from previous research. The newly reported MIS7 Oostermeer fauna (32.80–39.00 m b.s.) represents mostly full marine settings between storm wave base and fair-weather wave base. In composition and diversity, the MIS7 and MIS1 faunas strongly resemble and differ from the MIS5e fauna. This is the first well-documented record of three stacked marine interglacial assemblages from the southern North Sea Basin at one location. This new record enables us to make complete marine faunal characterisations of successive interglacial periods. Key implications for southern North Sea stratigraphy and palaeogeography are the resemblance of marine faunas and conditions in MIS7 and MIS1, the presence of a relatively warm latest MIS6 freshwater interval and confirmation and characterisation of the warm Eemian interval north of the classical type area.
