Jahn J Hornung

Benjamin P Kear, Sven Sachs

Conference Poster

Palaeobiology and Geobiology of Fossil Lagerstätten through Earth History

The Bückeberg Formation (Lower Saxony Basin, northern Germany and eastern Netherlands) represents a siliciclastic succession, deposited during the mid- Berriasian through to the earliest Valanginian. The unit is predominantly lacustrine with fluvial inflow and episodic marine connections to the Boreal Sea. Its fossil faunas include sauropterygian remains comprising isolated bones and partial, articulated skeletons. Though most of these finds cannot be identified at genus level, there is evidence of at least three morphotypes, representing distinct taxa: �Plesiosaurus degenhardti� Koken, 1887; Brancasaurus brancai Wegner, 1914; and an unnamed �pliosauromorph�. Other previously named taxa are dubious and/or may be synonymous. Articulated remains are concentrated to two abundance maxima in the Bückeberg Formation: the Obernkirchen Sandstone (lower Bückeberg Fm.) and Osterwald Mbr. (upper Bückeberg Fm.). The depositional environments of the former succession comprise freshwater lacustrine-deltaic barrier and mouthbar sandstones, and brackish deep-water pelites and littoral marls/calcarenites in the latter. The largely complete skeletons of B. brancai originate from a deep-water Konservat-Lagerstätte formed under brackish, euxinic conditions. These individuals are osteologically immature, which accords with other occurrences of limnic plesiosaurs and might infer ontogenetically controlled, migratorial behaviour.

English