Stable oxygen isotopes reveal different thermal regimes during the Early Pliocene in the southern North Sea Basin: a multi-species approach.

This article focuses on reconstructing Early Pliocene marine climatic conditions in the UK's Coralline Crag Formation using oxygen stable isotope (δ¹⁸O) analysis of four bivalve species. The study identifies two distinct seafloor temperature regimes—a warm-temperate setting (winter ~10 °C, summer >14 °C) represented by Centrocardita squamulosa ampla, Glycymeris obovata, and some Aequipecten opercularis, and a cold-temperate setting (winter ~6–7 °C, summer ~12 °C) represented by Arctica islandica and other Aequipecten opercularis specimens. These findings suggest glacial/interglacial-type climate fluctuations during deposition and highlight that fossil assemblages may reflect time-averaging of species from different climatic intervals rather than contemporaneous coexistence. The study also notes that thermal niches and growth phenology of these species appear consistent with those of their modern relatives, indicating ecological uniformitarianism is insufficient alone to interpret the paleoenvironment here.