Abstract In the North Sea basin the marine bivalve Macoma balthica first appears within the Early Pleistocene ‘Weybourne Crag’, which forms an important biostratigraphical datum. Here we review the fossil assemblages from sites of this age, prompted by new discoveries from Sidestrand, Norfolk, UK. The molluscan assemblages from this horizon are dominated by intertidal species with some colder/deeper water taxa and a few temperate non-marine species. A high boreal/low arctic marine environment with reduced salinities is indicated. An extensive assemblage of small mammals dominated by voles includes two species (Mimomys hordijki and Ungaromys dehmi) previously unknown from the British Pleistocene. The assemblage can be assigned to Tesakov’s Mammal Biozone MNR1 (=MN17, Middle Villafranchian), which according to current estimates corresponds to a date of ∼2.2-2.1 Ma (MIS 84-79). It matches another assemblage from -61 m to -65 m in the Zuurland-2 borehole in The Netherlands, and is similar to that from the Dutch Tiglian type site at Tegelen, although this has more temperate elements. A late Tiglian age is consistent with the co-occurrence of the marine bivalves Macoma balthica, Mya arenaria and the freshwater gastropod Viviparus glacialis in the Zuurland-2 borehole and in a North Sea borehole (BGS 52-02-472). A Macoma balthica – Mya arenaria Concurrent Range Zone is defined for this assemblage, which can be traced across the North Sea basin. Amino acid dating provides strong independent support for these correlations and indicates that the Baventian cold stage post-dates the Bramertonian (Norwich Crag). It also confirms that Early Pleistocene molluscan assemblages with M. balthica are younger than those without it. The correlation of this marine marker horizon with Mammal Biozone MNR1 provides a secure link between continental and marine sequences during the Early Pleistocene. It also provides a basis for dating events in the pre-glacial fluvial drainage history and linking it to the East European mammal zonation.

中文翻译：

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'Weybourne Crag' 的古生物学和年代测定，这是北海盆地南部早更新世的一个重要标志层

摘要 在北海盆地，海洋双壳类Macoma balthica 首次出现在早更新世'Weybourne Crag'内，形成了重要的生物地层数据。在这里，我们回顾了来自这个时代遗址的化石组合，这是由来自英国诺福克的 Sidestrand 的新发现推动的。这个地平线上的软体动物组合以潮间带物种为主，有一些较冷/较深的水类群和一些温带非海洋物种。显示了盐度降低的高北方/低北极海洋环境。由田鼠控制的大量小型哺乳动物包括两个在英国更新世以前未知的物种（Mimomys hordijki 和 Ungaromys dehmi）。该组合可以分配给 Tesakov 的哺乳动物生物区 MNR1 (=MN17, Middle Villafranchian)，根据目前的估计，这对应于~2.2-2.1 Ma（MIS 84-79）的日期。它与荷兰 Zuurland-2 钻孔中从 -61 m 到 -65 m 的另一个组合相匹配，并且类似于来自 Tegelen 的荷兰 Tiglian 型站点的组合，尽管它具有更多的温带元素。晚 Tiglian 时代与在 Zuurland-2 钻孔和北海钻孔 (BGS 52-02-472) 中同时出现海洋双壳类动物 Macoma balthica、Mya arenararia 和淡水腹足动物 Viviparus glacialis 一致。一个 Macoma balthica – Mya arenaria 并发范围区被定义为这个组合，可以在北海盆地追踪。氨基酸测年为这些相关性提供了强有力的独立支持，并表明巴文特冷期晚于布拉默顿期（诺维奇峭壁）。它还证实，带有 M. balthica 的早更新世软体动物组合比没有它的那些更年轻。该海洋标记层与哺乳动物生物区 MNR1 的相关性在早更新世期间提供了大陆和海洋序列之间的安全联系。它还为冰川前河流排水历史中的测年事件提供了基础，并将其与东欧哺乳动物分带联系起来。