Strophomenida

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Strophomenida
Temporal range: Ordovician–Carboniferous
An
bryozoan
.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Brachiopoda
Class: †Strophomenata
Order: †Strophomenida
Opik, 1934

Strophomenida is an extinct order of

genera[citation needed]. Some of the largest and heaviest known brachiopod species belong to this class. Strophomenids were among the most diverse and abundant brachiopods during the Ordovician, but their diversity was strongly impacted at the Late Ordovician mass extinction. Survivors rediversified into new morphologies in the Silurian,[2] only to be impacted once again at the Late Devonian mass extinction. However, they still survived till the mid Carboniferous.[1]

Adult strophomenids lack an opening for the pedicle (stalk), so in life, they either lay free or cemented the ventral valve (lower shell) onto a firm substrate at the umbo (hinge). In juveniles, a tiny hole for the pedicle was present on the ventral valve near the umbo, but this is closed up through development. The dorsal valve was typically concave or flat, though occasionally it was convex; the ventral valve was always convex. The hinge line at the rear of the shell was quite wide and strophic in shape, meaning that it was nearly straight. Many strophomenid shells are wider than long. The interior of the valves have a distinctive pseudopunctate microtexture: deflections in the mineralized shell layers stack up and unfurl into tiny bumps, which are usually supported by calcite rods known as a taleolae.[3]

Subtaxa (superfamilies)

Gallery

  • Strophomenid brachiopod with encrusting cornulitid tubeworm (Upper Ordovician, SE Indiana).
    Strophomenid brachiopod with encrusting cornulitid tubeworm (Upper Ordovician, SE Indiana).
  • Strophomenid brachiopod Leptaena from the Upper Ordovician of Iowa.
    Strophomenid brachiopod Leptaena from the Upper Ordovician of Iowa.

References

Wikispecies has information related to Strophomenata.
  1. ^
    doi:10.1146/annurev-earth-060115-012348
    .
  2. S2CID 92364910
    .
  3. ^ Williams, Alwyn; Brunton, C.H.C.; Carlson, S.J.; et al. (1997–2007). Kaesler, Roger L.; Selden, Paul (eds.). Part H, Brachiopoda (Revised). Treatise on Invertebrate Paleontology. Boulder, Colorado; Lawrence, Kansas: Geological Society of America; University of Kansas.
  4. ISSN 0031-0239
    .

Thompson, Ida (1982). National Audubon Society Field Guide to North American Fossils. New York: Alfred A. Knopf. pp. 648.

ISBN 0-394-52412-8
.


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