Rhynchonelliformea

Rhynchonelliformea is the name now given to the articulate brachiopods, Class Articulata, revised as a subphylum. Articulate brachiopods are those with hard, articulated, shells (hence the term) with a simple set of opening and closing muscles.

The name, Rhynchoelliformea, which replaces Articulata, which is also a class of crinoids, comes from the family Rhynchonellidae, which however is no more representative of articulate brachiopods than any other group such as spirifers or strophomenids. It just happens to be the name chosen, based on an included taxon.

The main difference between the Rhynchonelliformea described in the Treatise Part H, revised 2000/2007, and the Articulata of the Treatise part H, 1965, lies in the groups included, their taxonomic positions and arrangements. The Rhynchonelliformea (Articulata revised) is divided into five classes: Obolellata, Kutorginata, Chileata, Strophomenata, and Rhynchonellata. The Strophomenata and Rhynchonellata are found living today; the Rhynchellata as the major constituent of modern brachiopod faunas, the Stromphomenata as only a minor contributor. The Obolellata, Kutorginata, and Chileata are all extinct. The Obolellata and Kutorginata are restricted to the Cambrian, the Chileata ranges throughout the extent of the Paleozoic.