Spiriferida is an order of extinct articulate

brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s which are known for their long hinge-line, which is often the widest part of the shell. In some genera (e.g. ''

Mucrospirifer ''Mucrospirifer'' is a genus of extinct brachiopods in the class Rhynchonellata (Articulata) and the order Spiriferida. They are sometimes known as "butterfly shells". Like other brachiopods, they were filter feeders. These fossils occur mainly ...

'') it is greatly elongated, giving them a wing-like appearance. They often have a deep fold down the center of the shell. The feature that gives the spiriferids their name ("spiral-bearers") is the internal support for the

lophophore The lophophore () is a characteristic feeding organ possessed by four major groups of animals: the Brachiopoda, Bryozoa, Hyolitha, and Phoronida, which collectively constitute the protostome group Lophophorata.Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

with the appearance of '' Eospirifer radiatus''. They increased in diversity throughout the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

and underwent a dramatic

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

ary radiation during the

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

period, reaching peak development in variety and numbers. Spiriferida survived the great Permian extinction (Albeit at much less diversity), finally becoming extinct during the Early to Middle

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

. Fossils of this order are often preserved as

pyrite The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...

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 (syn. Cyrtiacea) ***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

References

Introduction to the Spiriferida
at berkeley.edu

at the Paleos website * Zhan, RenBin, JiSuo Jin, Yan Liang, and LingKai Meng. "Evolution and paleogeography of Eospirifer (Spiriferida, Brachiopoda) in Late Ordovician and Silurian." Science China Earth Sciences 55, no. 9 (2012): 1427–1444. {{Brachiopod orders Prehistoric brachiopod orders