en Strophomenata

Strophomenata; Temporal range: Cambrian Stage 4-Triassic,; 516-205 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Strophomenid brachiopod with encrusting cornulitid worm tube (Upper Ordovician, SE Indiana).
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Brachiopoda
Subphylum:	Rhynchonelliformea
Class:	†Strophomenata; Williams 1996
Orders
	†Billingsellida; †Orthotetida; †Productida; †Strophomenida;

Strophomenata is an extinct class of brachiopods in the subphylum Rhynchonelliformea.

They originated in the Cambrian period, hugely diversified during the Ordovician, and faced near extinction from the Permian-Triassic extinction. Only a few lingered around in the Triassic until eventually going extinct.^[2] They were an exceptionally diverse group of brachiopods, and within the group the Strophomenids of the early Paleozoic and Productids of the late Paleozoic hugely contributed to the immense diversity.

Common Features

In The phylogeny and classification of Rhynchonelliformea, Strophomenates are described as having "no definite synapomorphies". A number of common features appear throughout the group, but there are many exceptions and none are universal to the group.

The common features of the Strophomenates include:

concavo-convex(sometimes convexi-concave), or plano-convex shells;
a laminar secondary shell layer with well developed pseudopunctae (microstructural features);
a bilobed cardinal process;
the existence of the pseudodeltidium;
a supra-apical/apical foramen, at least during juvenile stages, which is a feature associated to the egression of the pedicle during growth(many Strophomenates lose their pedicles after certain age).^[2]

Orders

Billingsellida

An order that contains the suborder Clitambonitidina (and others?) .

Orthotetida

An order or superfamily that includes the Chilidiopsoidea.^[3] Ontogeny given by Bassett and Popov (2017), resembling that of Kutorginides.^[3]

Believed to be sister to Strophomenides, = Strophomenida + Billinsellida + Productida.^[4]

Includes the Chileids (e.g. Coolinia).

Strophomenida

Originating in the Early Ordovician and persisting until the Carboniferous, the Strophomenids were an extremely diverse order. Strophomenids are usually divided into two groups - the Plectambonitoidea and the Strophomenoidea.^[5] Some members used their short meaty pedicles for attachment, while many others lost their pedicle during growth and developed a free-lying lifestyle.^[6] As such a lot of their shells are concavo-convex. Microstructural features of the Strophomenid shell include a cross-laminar structure, and a pseudopunctate laminar layer often found with taleolae.^[2] Well-known Strophomenids include Leptaena, Sowerbyella, Rafinesquina, and Strophomena.

References

^ Paleobiology Database
^ ^a ^b ^c Carlson, Sandra J.; Leighton, Lindsey R. (2001). "The Phylogeny and Classification of Rhynchonelliformea". The Paleontological Society Papers. 7: 27–52. doi:10.1017/S1089332600000887. ISSN 1089-3326.
^ ^a ^b LE Holmer, Z Zhang, TP Topper, and L Popov 2017. The attachment strategies of Cambrian kutorginate brachiopods: the curious case of two pedicle openings and their phylogenetic significance. Journal of Paleontology, 2017.
^ Bassett, M.G., and Popov, L.E. (2017). Earliest ontogeny of the Silurian orthotetide brachiopod ~Coolinia~ and its significance for interpreting strophomenate phylogeny. Lethaia 50, 504–510.
^ Congreve, Curtis R.; Krug, Andrew Z.; Patzkowsky, Mark E. (2015). Sevastopulo, George (ed.). "Phylogenetic revision of the Strophomenida, a diverse and ecologically important Palaeozoic brachiopod order". Palaeontology. 58 (4): 743–758. Bibcode:2015Palgy..58..743C. doi:10.1111/pala.12177.
^ Hoel, Ole A. (2014-01-21). "Palaeobiology of Silurian Leptaeninae (Brachiopoda) from Gotland, Sweden". Paleontology Journal. 2014: 1–14. doi:10.1155/2014/716053. ISSN 2314-4289.