Terebratulids

Terebratulids are a prominent group of brachiopods, characterized by their biconvex, smooth shells. They are articulate brachiopods, meaning their shells are articulated by a more complex hinge mechanism than in inarticulate brachiopods. A defining feature of terebratulids is the presence of a pedicle, a fleshy stalk that extends from the ventral (lower) valve, which they use to attach themselves to substrates such as rocks or shells. The shell shape is typically oval or ovate, with the ventral valve being slightly larger than the dorsal (upper) valve. Internally, terebratulids possess a distinctive loop of calcareous support for their feeding organs, known as the lophophore.

These marine invertebrates are found in a wide range of marine environments, from shallow coastal waters to the deep sea, and from tropical to polar regions. Their fossil record is extensive, with terebratulids being among the most common fossils found in many sedimentary rock formations. They were particularly abundant during the Mesozoic Era. Today, terebratulids are still extant, though their diversity is significantly less than in past geological periods. They are suspension feeders, using their lophophore to filter food particles from the water. Their slow-moving nature and reliance on currents for food make them sensitive to environmental changes.