The position of the Banwell Bone Cave mammal assemblage zone (MAZ) in the mammalian biostratigraphy of the British Isles has been the focus of debate for decades. Dominated by fauna typical of cold environments it was originally linked to the marine oxygen isotope stage (MIS) 4 stadial (ca. 72–59 ka). Subsequently it was argued that the Banwell Bone Cave MAZ more likely relates to the temperate interstadial of MIS 5a (ca. 86–72 ka). It is envisioned that “cold fauna” such as bison and reindeer moved into Britain during stadial MIS 5b (ca. 90 ka) and were subsequently isolated by the rising sea level during MIS 5a. Here we investigate environmental conditions during the Banwell Bone Cave MAZ using bone collagen δ13C and δ15N and tooth enamel δ18O and δ13C isotope analysis. We analyse bison and reindeer from the MAZ type-site, Banwell Bone Cave. Our results show unusually high δ15N values, which we ascribe to arid conditions within a temperate environment. Palaeotemperature estimates derived from enamel δ18O indicate warm temperatures, similar to present day. These results confirm that the Banwell Bone Cave MAZ relates to a temperate interstadial and supports its correlation to MIS 5a rather than MIS 4.

中文翻译：

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稳定同位素证实班韦尔骨洞哺乳动物组合区代表 MIS 5 动物群

几十年来，班威尔骨洞哺乳动物聚集区 (MAZ) 在不列颠群岛哺乳动物生物地层学中的位置一直是争论的焦点。它以寒冷环境中典型的动物群为主，最初与海洋氧同位素阶段 (MIS) 4 stadial (ca. 72–59 ka) 有关。随后有人认为，Banwell Bone Cave MAZ 更可能与 MIS 5a（约 86-72 ka）的温带间质有关。据设想，野牛和驯鹿等“寒冷动物群”在 MIS 5b（约 90 ka）期间进入英国，随后在 MIS 5a 期间因海平面上升而被隔离。在这里，我们使用骨胶原 δ 研究 Banwell Bone Cave MAZ 期间的环境条件13C和δ15N和牙釉质δ18O 和 δ13C同位素分析。我们分析来自 MAZ 类型遗址 Banwell Bone Cave 的野牛和驯鹿。我们的结果显示异常高的 δ15N 值，我们将其归因于温带环境中的干旱条件。来自珐琅质δ的古温度估计18O 表示温暖的温度，类似于现在。这些结果证实，Banwell Bone Cave MAZ 与温带间质有关，并支持其与 MIS 5a 而不是 MIS 4 的相关性。