Brachiopoda Official

Unlike bivalve mollusks (clams), brachiopod shells are symmetrical across a vertical plane (between the valves) rather than a horizontal plane.

Severely impacted by the end-Permian extinction (~252 Ma), losing most of their diversity. brachiopoda

Lingula (an inarticulate) is considered a "living fossil," remaining virtually unchanged for over 500 million years. IV. Evolutionary History and Paleontology Unlike bivalve mollusks (clams)

Features a body that takes up less space inside the shell than a bivalve, with a complex lophophore filling most of the space. III. Classification and Key Subphyla making them the most common fossils.

Possess a toothed hinge for opening shells, making them the most common fossils.