The Rhynchonellata is a class of articulate brachiopods that combines certain orders from within the Rhynchonelliformea (Articulata revised). The class ranges from the Lower Cambrian to Recent.
Orders included in the Rhynchonellata are the Rhynchonellida, Orthida, Pentamerida, Atrypida, Athyridida, Spiriferida, Spiriferinida and Terebratulida. The Atrypida, Athyridida, and Spiriferinida were originally included in the Spiriferida as suborders. The Atrypida is the Atrypacea, the Athyridida, the Rostropiracea and the Spiriferinida the Punctospiracea of Moore, Lalicker, and Fischer.[clarification needed]
The Orthida and Spiriferida have wide hinge lines . The Pentamerida, Terebratulida, Atripida and Athyridida have narrow hinge lines. The Orthida, Pentamerida, Rhynchonellida, and Terebratulida have looped brachidia[clarification needed]. The Spiriferida, Atrypida, Athyridida, and Spiriferinida have spiral brachidia. Some, like the Rhynchonellida and Spiriferida, may be strongly plicate,[clarification needed] with a median fold and sulcus.[clarification needed] Others, like the Spiriferinida and Terebratulida are basically smooth. All a primarily or exclusively impunctate[clarification needed] but some e.g. Orthida and Rhynchonellida have puctate[clarification needed] off shoots.
* Moore, Lalicker, and Fischer 1952. Invertebrate Fossils, Ch 6, Brachiopoda, R.C. Moore
Source: Wikipedia, Wikispecies: All text is available under the terms of the GNU Free Documentation License