What is "caprinidae"

Caprinidae is a family of rudists, a group of unusual fossil saltwater clams, marine heterodont bivalves in the order Hippuritoida.

These stationary intermediate-level epifaunal suspension feeders lived in the Cretaceous period, from 140.2 to 66.043 Ma. The rudists became extinct at the end of the Cretaceous, apparently as a result of the Cretaceous–Paleogene extinction event.

Fossils of this genus have been found in the sediments of Europe, China, Cuba, Egypt, Guatemala, Jamaica, Japan, Mexico, Oman, Philippines, Turkey, Russia, United States, Venezuela.