Strophomenidines

Strophomenidines are an extinct group of brachiopods that lived during the Ordovician and Silurian periods. They belong to the order Strophomenida, a large and diverse group of articulate brachiopods characterized by their shells, which were typically flattened and often ornamented with concentric growth lines and radial ribs. Strophomenidines are distinguished by specific features of their brachial (upper) and pedicle (lower) valves. The brachial valve generally possesses a well-developed internal hinge plate, and the pedicle valve often shows a pitted or impunctate shell structure. Their ventral interarea, the area around the hinge, was typically large and strongly arched.

These brachiopods were common in marine environments, inhabiting a range of seafloor substrates. Their flattened shells may have aided in preventing them from sinking into soft sediments or allowed them to lie flat on hard surfaces. Fossil evidence suggests that strophomenidines were sessile, attaching themselves to the substrate or simply resting on the seafloor. They were filter feeders, drawing water into their shells to extract microscopic food particles. The extinction of strophomenidines likely occurred by the end of the Silurian period, though their evolutionary lineage contributed to later brachiopod groups. Their fossils are valuable for understanding Paleozoic marine ecosystems and biostratigraphy.