Strophomenidina

Strophomenidina is an extinct suborder of articulate brachiopods that lived from the Late Cambrian to the Late Permian periods. They are characterized by their dorsal valve being convex and their ventral valve being concave or nearly flat. This unusual orientation, often referred to as resiliate, distinguishes them from other articulate brachiopods where the ventral valve is typically more convex. The shell material of strophomenidines was impunctate, meaning it lacked perforations.

These brachiopods were predominantly sessile, attaching themselves to substrates like sediment or other organisms. Their feeding mechanism involved filtering small particles from the water column using their lophophore, a specialized organ. Strophomenidines exhibited a wide range of shell morphologies, from simple, rounded forms to more elaborate, frilled, or spiny structures. Their ornamentation often included concentric growth lines and radial ribs.

Fossil strophomenidines are found globally in marine sedimentary rocks. They were ecologically important in Paleozoic marine communities, occupying various niches. Their diverse forms and widespread distribution have made them valuable index fossils for dating and correlating rock layers from the Cambrian through the Permian. The suborder is divided into several superfamilies, reflecting their evolutionary diversification throughout the Paleozoic Era. Their extinction at the end of the Permian coincides with the end-Permian mass extinction event.