Evolution of the genus Cribroconcha (Ostracoda, Crustacea) in relationship to palaeoecological changes during the late Palaeozoic

Abstract To date, 37 species and 2 subspecies (36 species plus 1 species that with 2 subspecies) of the ostracode genus Cribroconcha Cooper, 1941 have been reported worldwide, ranging in age from the Middle Devonian to the Early Permian with an acme during the Carboniferous. Based on the geographical distribution and morphological characteristics of Cribroconcha, two evolutionary lineages (i.e., Lineage 1 and Lineage 2) are identified, which originated in the European and the Kazakhstan plates, respectively. Lineage 1 can be subdivided into three types: 1-A (stable type), 1-B (reshaped type) and 1-C (spiny type). Lineage 2 has a simpler pattern of evolution compared to Lineage 1. Although there were certain accompanying changes in the morphology of carapaces, the general pattern and most successful evolutionary novelty of Cribroconcha appears to be the appearance of spiny forms in the Early Carboniferous, which continued to be preserved until the Early Permian. The habitats of Cribroconcha may have changed from shallow, warm waters to deep, calm and colder waters in the basinal environments. Four Cribroconcha biozones, extending from the Givetian Stage to Serpukhovian Stage are established in the Euramerica plate, namely C. beckmanni Zone, C. triquetra triquetra Zone, C. cooperi Zone and C. caneyensis Zone.