Revision of the British Lower Jurassic Astartinae (Bivalvia).

This article focuses on the taxonomic revision of the Astartinae subfamily of the Astartidae bivalves from the British Lower Jurassic, aiming to clarify genus and species distinctions to better understand their evolutionary and extinction patterns. It recognizes three genera—Neocrassina, Coelastarte, and Oxyeurax—and describes twelve species, including three new species, while questioning the generic placement of some taxa traditionally assigned to Neocrassina and Nicaniella. The study highlights the influence of ontogeny, potential protandric sexual dimorphism, and environmental factors on shell morphology and ornamentation, complicating species differentiation. It also discusses the impact of the Early Toarcian extinction event on these bivalves, noting a significant reduction in diversity, and emphasizes the need for ongoing taxonomic refinement to support paleoecological and evolutionary research.