Pterioids

Pterioids are an extinct suborder of bivalve mollusks belonging to the order Pterioida. They are characterized by their inequivalve shells, meaning the two valves are different in size and shape, and often by their byssal gape, a notch or opening in the shell through which byssal threads could be extended. These threads were used for attachment to hard substrates such as rocks, other shells, or even coral reefs.

The fossil record of pterioids is extensive, with many species found from the Devonian period to the present day, though many lineages became extinct. They were a diverse group, inhabiting a wide range of marine environments, from shallow coastal waters to deeper offshore areas. Their ecological roles varied, with some acting as filter feeders, while others may have played a role in sediment stabilization.

Notable extinct families within the pterioids include the Gryphaeidae, known for their often irregular and inflated shells, and the Pinnidae, which were large, fan-shaped bivalves that lived vertically embedded in soft sediments, using their byssus to anchor themselves. While the suborder Pterioida contains extant families like the Pteriidae (pearl oysters), the classification and precise boundaries of the extinct pterioids are subject to ongoing paleontological research. The study of pterioids provides valuable insights into the evolution of bivalve life and the paleoecology of ancient marine ecosystems.