Rhynchonellata
Encyclopedia
The Rhynchonellata is a class of articulate
brachiopod
s 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.
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. The Spiriferida, Atrypida, Athyridida, and Spiriferinida have spiral brachidia. Some, like the Rhynchonellida and Spiriferida, may be strongly plicate, with a median fold and sulcus. Others, like the Spiriferinida and Terebratulida are basically smooth. All a primarily or exclusively impunctate but some e.g. Orthida and Rhynchonellida have puctate off shoots.
Articulata (Brachiopoda)
The Articulata is a class of brachiopods which comprises those with hinged, calcareous shells that generally bear well developed teeth and sockets and a simple muscle system...
brachiopod
Brachiopod
Brachiopods are a phylum of marine animals that have hard "valves" on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection...
s that combines certain orders from within the Rhynchonelliformea
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 with a simple set of opening and closing muscles....
(Articulata revised). The class ranges from the Lower Cambrian to Recent.
Orders included in the Rhynchonellata are the Rhynchonellida
Rhynchonellida
The taxonomic order Rhynchonellida is one of the two main groups of living articulate brachiopods, the other being the order Terebratulida. They are recognized by their strongly ribbed wedge-shaped or nut-like shells, and the very short hinge line....
, Orthida
Orthida
Orthida is an extinct order of Brachiopods which appeared during the Early Cambrian period and became very diverse by the Ordovician, living in shallow-shelf seas. Orthids are the oldest member of the subphylum Rhynchonelliformea , and is the order from which all other brachiopods of this group...
, Pentamerida
Pentamerida
Pentamerida is a brachiopods order in the class Rhynchonellata.Pentamerida have narrow hinge lines and looped brachidia....
, Atrypida, Athyridida, Spiriferida
Spiriferida
Spiriferida is an order of extinct articulate brachiopod fossils which are known for their long hinge-line, which is often the widest part of the shell. In some genera it is greatly elongated, giving them a wing-like appearance. They often have a deep fold down the center of the shell...
, Spiriferinida and Terebratulida
Terebratulida
Terebratulids are one of only three living orders of articulate brachiopods, the others being the Rhynchonellida and the Thecideida. Craniida and Lingulida include living brachiopods, but are inarticulates. The name, Terebratula, may be derived from the Latin "terebra", meaning "hole-borer"...
. 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.
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. The Spiriferida, Atrypida, Athyridida, and Spiriferinida have spiral brachidia. Some, like the Rhynchonellida and Spiriferida, may be strongly plicate, with a median fold and sulcus. Others, like the Spiriferinida and Terebratulida are basically smooth. All a primarily or exclusively impunctate but some e.g. Orthida and Rhynchonellida have puctate off shoots.