Spiriferida

Spiriferida is an extinct order of brachiopods, known from the Ordovician to the Triassic.

Description

The order Spiriferida belongs to the subphylum Rhynchonelliformea, approximately corresponding to the former subphylum Articulata characterised by calcareous shell with teeth and sockets, and to the class Rhynchonellata defined on the basis of the shell microstructure.
The spiriferides are characterised by a spiralium that is oriented laterally or postero-laterally, the absence of a jugum, and an impunctate shell. The two latter characters allow the distinction between the orders Spiriferida and Spiriferinida. These two orders were merged in older brachiopod systems, which explains information about Jurassic spiriferides being found in older sources. The feature that gives both the spiriferides and the spiriferinides their name is the internal support for the lophophore; this brachidium, which is sometimes preserved in fossils, is a thin ribbon of calcite that is coiled tightly within the shell forming a cone.
Externally, the spiriferides are known for their costate shells with a 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. However, some spiriferides have quite different shell shapes.

Stratigraphic range

Spiriferides first appear in the Late Ordovician with the appearance of Eospirifer radiatus. They increased in diversity throughout the Silurian and underwent a dramatic evolutionary radiation during the Devonian period, reaching peak development in variety and numbers. Spiriferida survived the great Permian extinction, finally becoming extinct during the Triassic.
Image:HederellaOH3.jpg|thumb|A Devonian spiriferide brachiopod from Ohio which served as a host substrate for a colony of hederellids.

Taxonomy

Order Spiriferida

Suborder Delthyridina
*Superfamily Delthyridoidea
**Family Acrospiriferidae
**Family Cyrtinopsidae
**Family Delthyrididae
**Family Hysterolitidae
**Family Mucrospiriferidae
*Superfamily Reticularioidea
**Family Elythidae
**Family Reticulariidae
**Family Thomasariidae
**Family Xenomartiniidae
Suborder Spiriferidina
*Superfamily Adolfioidea
**Family Adolfiidae
**Family Echinospiriferidae
*Superfamily Ambocoelioidea
**Family Ambocoeliidae
**Family Eudoxinidae
**Family Lazutkiniidae
**Family Verneuiliidae
*Superfamily Brachythyridoidea
**Family Brachythyrididae
**Family Skelidorygmidae
*Superfamily Cyrtioidea
**Family Costispiriferidae
**Family Cyrtiidae
**Family Hedeinopsidae
*Superfamily Cyrtospiriferoidea
**Family Conispiriferidae
**Family Cyrtospiriferidae
**Family Spinocyrtiidae
*Superfamily Martinioidea
**Family Crassumbidae
**Family Elythynidae
**Family Gerkispiridae
**Family Ingelarellidae
**Family Martiniidae
**Family Perissothyrididae
**Family Tenellodermidae
*Superfamily Paeckelmanelloidea
**Family Paeckelmanellidae
**Family Strophopleuridae
*Superfamily Spiriferoidea
**Family Choristitidae
**Family Imbrexiidae
**Family Reticulariacea
**Family Spiriferellidae
**Family Spiriferidae
**Family Trigonotretidae
*Superfamily Theodossioidea
**Family Palaeochoristitidae
**Family Theodossiidae
**Family Ulbospiriferidae