Rostroconchia

Rostroconchia is an extinct class of marine bivalve molluscs. These ancient creatures lived from the Early Cambrian to the Late Devonian periods. They are characterized by a distinctive shell morphology that evolved over time. Early forms possessed a single, conical shell, while later members developed a two-part shell that superficially resembled that of modern bivalves, though their internal anatomy and evolutionary relationships differ significantly.

The name Rostroconchia derives from Latin words meaning "beak" and "shell," referring to the characteristic beak-like projection of their shells. Fossil evidence suggests that rostroconchs were burrowing organisms, inhabiting soft substrates on the seafloor. Their diet likely consisted of detritus or small organisms filtered from the sediment. The precise phylogenetic position of Rostroconchia within Mollusca has been a subject of debate, but they are generally considered an early offshoot from the main lineage that led to modern bivalves and other related groups. Their extinction marks the end of a significant branch of early marine invertebrate life.