Caprinidae

Caprinidae is a family of extinct bivalve mollusks belonging to the order Hippuritida. These marine organisms lived during the Cretaceous period, from the Albian to the Campanian stages, approximately 113 to 72 million years ago. They are characterized by their complex, often irregular shells and their association with ancient reef environments.

The most distinctive feature of Caprinidae is the presence of two significantly unequal valves. The lower valve, or RV (right valve), was typically large, conical, or cylindrical, and firmly attached to the substrate. This valve often bore prominent radial ribs or other sculptural elements. The upper valve, or LV (left valve), was smaller and served as a lid, fitting into a corresponding depression on the RV. Internally, the shells featured complex pallial muscle scars and often large, fused pallial sinuses.

Caprinids were sessile, filter-feeding organisms that played a crucial role in the formation of Cretaceous carbonate platforms and reefs. Their rapid growth and accumulation contributed significantly to the sedimentary record of the time. They are known from fossil deposits worldwide, particularly in Tethyan and Indo-Pacific regions. Notable genera within the family include Caprina, Coalcomana, and Offneria. The extinction of Caprinidae, along with other rudist bivalves, is associated with the end-Cretaceous mass extinction event.