# Trimerellida

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Extinct order of brachiopods

Trimerellida Temporal range: Darriwilian–Ludlow[1] PreꞒ Ꞓ O S D C P T J K Pg N Dinobolus davidsoni, a trimerellid from the Silurian of Estonia Scientific classification Kingdom: Animalia Phylum: Brachiopoda Class: Craniata Order: †Trimerellida Gorjansky & Popov, 1985 Superfamily: †Trimerelloidea Davidson & King, 1872 Families See text.

**Trimerellida** is an [extinct](/source/Extinction) [order](/source/Order_(biology)) of [craniate](/source/Craniata_(brachiopod)) [brachiopods](/source/Brachiopod), containing the sole [superfamily](/source/Superfamily_(biology)) **Trimerelloidea** and the [families](/source/Family_(taxonomy)) [Adensuidae](https://en.wikipedia.org/w/index.php?title=Adensuidae&action=edit&redlink=1), [Trimerellidae](/source/Trimerellidae), and [Ussuniidae](/source/Ussuniidae). Trimerellidae was a widespread family of warm-water brachiopods ranging from the Middle [Ordovician](/source/Ordovician) ("Llandeilo" / [Darriwilian](/source/Darriwilian)) to the late Silurian ([Ludlow](/source/Ludlow_epoch)). Adensuidae and Ussuniidae are monogeneric families restricted to the Ordovician of [Kazakhstan](/source/Kazakhstan).[2] Most individuals were free-living, though some (namely Australian populations of the genus *[Eodinobolus](https://en.wikipedia.org/w/index.php?title=Eodinobolus&action=edit&redlink=1)*) clustered into large congregations similar to modern [oyster reefs](/source/Oyster_reef).[2][3]

## Evolution

Trimerellides probably originated from tropical [island arcs](/source/Island_arc) in the region of [Kazakhstania](/source/Kazakhstania) (present-day Kazakhstan) during the "Llandeilo" (late Darriwilian stage). By the late [Sandbian](/source/Sandbian) and early [Katian](/source/Katian) stages, many dispersed eastward to nearby regions equivalent to [South China](/source/South_China_craton) and Australia. A few managed to populate the vicinity of [Laurentia](/source/Laurentia) (North America), possibly through its diminishing proximity to the Australian portion of [Gondwana](/source/Gondwana). By the late Katian, trimerellides had also dispersed westward, populating the seas around [Baltica](/source/Baltica) (eastern Europe), Scotland, and [Siberia](/source/Siberia_(continent)). Trimerellides were an exclusively tropical group, with most genera [endemic](/source/Endemism) to a specific region. There are some exceptions: *Eodinobolus* and *[Monomerella](https://en.wikipedia.org/w/index.php?title=Monomerella&action=edit&redlink=1)* were particularly widespread, found at low-latitude ecosystems worldwide.[4] At their acme in the late Katian, trimerellides reached the highest diversity ever seen among [craniiform](/source/Craniiforma) brachiopods, forming a significant component of brachiopod assemblages worldwide.[2][5]

Trimerellide diversity collapsed during global cooling in the first pulse of the [Late Ordovician mass extinction](/source/Late_Ordovician_mass_extinction).[6] This fate was shared by several other orders of "[inarticulate](/source/Inarticulata)" brachiopods.[5] Trimerellides are an example of a [Lazarus taxon](/source/Lazarus_taxon): their fossils are absent from the [Hirnantian](/source/Hirnantian) (last stage of the Ordovician) and the [Rhuddanian](/source/Rhuddanian) (first stage of the Silurian), with only a few new Silurian genera afterwards.[6][4][2] Silurian species were most likely descended from relictual survivors in South China and Australia. Trimerellides managed to recover slightly during the late [Wenlock Epoch](/source/Wenlock_Epoch) (mid-Silurian), experiencing a mild rediversification at the species level. New species emphasized deeper muscle attachments relative to most of their Ordovician counterparts. Silurian trimerellide species may have been too specialized to adapt to rapid changes, resulting in their total extinction in the [Ludlow Epoch](/source/Ludlow_Epoch).[7]

## Anatomy

Trimerellides are massive by the standards of early brachiopods. They have fairly smooth and unornamented shells, which were probably [aragonitic](/source/Aragonite) in composition. The shells are unequally biconvex (both [valves](/source/Valve_(mollusc)) convex to different degrees), in some cases nearly spherical in shape.[2] There is no opening for the pedicle. Trimerellides show some similarities to [rhynchonelliform](/source/Rhynchonelliformea) ("articulate") brachiopods, including mixoperipheral shell growth (where the valves converge towards each other) and the development a fixed hinge at the back of the shell. In trimerellides, this hinge is an articulation between a wide plate on the dorsal valve and a socket-like groove on the ventral valve, opposite to the socket-and-teeth articulation of rhynchonelliforms.[2]

Like other craniate brachiopods, the [musculature](/source/Musculature) consisted of two pairs of large and vertically-oriented [adductor muscles](/source/Adductor_muscles_(bivalve)) (which close the shell) alongside two pairs of horizontally-oriented oblique muscles (which slide each valve past each other). The inner (internal) pair of oblique muscles extend nearly straight back to the dorsal valve hinge plate. This contrasts with [craniids](/source/Craniidae) and [craniopsids](/source/Craniopsidae), where the oblique internals splay out and attach besides the posterior adductors. A shelf is usually present near the middle of each valve, in front of the attachments for the anterior adductors.[2] In later trimerellides especially, the anterior adductors sockets are deep vaulted pockets hollowed out from the internal surface of each valve.[7]

## Subgroups

From the *[Treatise on Invertebrate Paleontology](/source/Treatise_on_Invertebrate_Paleontology) Part H, Revised* (unless stated otherwise):[2]*[8]*

- Family Adensuidae Popov & Rukavishnikova, 1986 - *[Adensu](https://en.wikipedia.org/w/index.php?title=Adensu&action=edit&redlink=1)* Popov & Rukavishnikova, 1986 [Upper Ordovician ("Caradoc" – "Ashgill")]

- Family Trimerellidae Davidson & King, 1872 - *[Belubula](https://en.wikipedia.org/w/index.php?title=Belubula&action=edit&redlink=1)* Percival, 1995 [Upper Ordovician ("Caradoc" – "Ashgill"?)] - *[Bowanpodium](https://en.wikipedia.org/w/index.php?title=Bowanpodium&action=edit&redlink=1)* Percival, 1995 [Upper Ordovician ("Caradoc")] - *[Corystops](https://en.wikipedia.org/w/index.php?title=Corystops&action=edit&redlink=1)* Percival, 1995 [Upper Ordovician ("Caradoc")] - *[Costitrimella](https://en.wikipedia.org/w/index.php?title=Costitrimella&action=edit&redlink=1)* Rong & Li, 1993 [Upper Ordovician ("Ashgill")] - *[Dinobolus](https://en.wikipedia.org/w/index.php?title=Dinobolus&action=edit&redlink=1)* Hall, 1871 [lower-mid Silurian (Llandovery – Wenlock)] - *[Eodinobolus](https://en.wikipedia.org/w/index.php?title=Eodinobolus&action=edit&redlink=1)* Rowell, 1963 [Upper Ordovician ("Caradoc" – "Ashgill")] - *[Fengzuella](https://en.wikipedia.org/w/index.php?title=Fengzuella&action=edit&redlink=1)* Li & Han, 1980 [Upper Ordovician ("Ashgill")] - *[Gasconsia](/source/Gasconsia)* Northrop, 1939 [Upper Ordovician ("Ashgill") – upper Silurian (Ludlow)] - *[Gyroselenella](https://en.wikipedia.org/w/index.php?title=Gyroselenella&action=edit&redlink=1)*? Li, 1985 = *Selenella* [Upper Ordovician ("Ashgill")] - *[Keteiodoros](https://en.wikipedia.org/w/index.php?title=Keteiodoros&action=edit&redlink=1)* Strusz et al., 1998 [mid-Silurian (Wenlock)] - *[Monomerella](https://en.wikipedia.org/w/index.php?title=Monomerella&action=edit&redlink=1)* Billings, 1871 [Upper Ordovician ("Caradoc") – mid-Silurian (Wenlock)] - *[Ovidiella](https://en.wikipedia.org/w/index.php?title=Ovidiella&action=edit&redlink=1)* Nikitin & Popov, 1984 [Middle Ordovician ("Llandeilo") – Upper Ordovician ("Caradoc")] - *[Palaeotrimerella](https://en.wikipedia.org/w/index.php?title=Palaeotrimerella&action=edit&redlink=1)* Li & Han, 1980 [Middle Ordovician ("Llandeilo") – Upper Ordovician ("Ashgill")] - *[Paradinobolus](https://en.wikipedia.org/w/index.php?title=Paradinobolus&action=edit&redlink=1)* Li & Han, 1980 [Upper Ordovician ("Ashgill")] - *[Peritrimerella](https://en.wikipedia.org/w/index.php?title=Peritrimerella&action=edit&redlink=1)* Liang, 1983 [Upper Ordovician ("Ashgill")] - *[Porcidium](https://en.wikipedia.org/w/index.php?title=Porcidium&action=edit&redlink=1)* Percival, 1995 [Upper Ordovician ("Caradoc")] - *[Rhynobolus](https://en.wikipedia.org/w/index.php?title=Rhynobolus&action=edit&redlink=1)* Hall, 1871 [mid-Silurian (Wenlock)] - *[Sinotrimerella](https://en.wikipedia.org/w/index.php?title=Sinotrimerella&action=edit&redlink=1)* Li & Han, 1980 [Upper Ordovician ("Ashgill")] - *[Trimerella](https://en.wikipedia.org/w/index.php?title=Trimerella&action=edit&redlink=1)* Billings, 1862 [Upper Ordovician ("Ashgill") – mid-Silurian (Wenlock)] - *[Yidurella](https://en.wikipedia.org/w/index.php?title=Yidurella&action=edit&redlink=1)* Zeng, 1987 [lower Silurian]

- Family [Ussuniidae](/source/Ussuniidae) Nikitin & Popov, 1984 - *[Ussunia](https://en.wikipedia.org/w/index.php?title=Ussunia&action=edit&redlink=1)* Nikitin & Popov, 1984 [Middle Ordovician ("Llandeilo") – Upper Ordovician ("Caradoc")]

## References

1. **[^](#cite_ref-1)** ["Palaeos Metazoa: Brachiopoda: Trimerellida"](http://palaeos.com/metazoa/brachiopoda/trimerellida.html).

1. ^ [***a***](#cite_ref-:2_2-0) [***b***](#cite_ref-:2_2-1) [***c***](#cite_ref-:2_2-2) [***d***](#cite_ref-:2_2-3) [***e***](#cite_ref-:2_2-4) [***f***](#cite_ref-:2_2-5) [***g***](#cite_ref-:2_2-6) [***h***](#cite_ref-:2_2-7) Popov, Leonid E.; Holmer, Lars E. (2000). ["Chapter 2 (part): Trimerellida"](https://journals.ku.edu/InvertebratePaleo/article/view/5207/4685). In Kaesler, Roger L. (ed.). [*Part H, Brachiopoda (Revised). Volumes 2 & 3: Linguliformea, Craniiformea, and Rhynchonelliformea (part)*](https://journals.ku.edu/InvertebratePaleo/article/view/5207). [Treatise on Invertebrate Paleontology](/source/Treatise_on_Invertebrate_Paleontology). Boulder, Colorado; Lawrence, Kansas: Geological Society of America; University of Kansas. pp. 184–192. [ISBN](/source/ISBN_(identifier)) [0-8137-3108-9](https://en.wikipedia.org/wiki/Special:BookSources/0-8137-3108-9).

1. **[^](#cite_ref-3)** WEBBY, BARRY D.; PERCIVAL, IAN G. (1983). ["Ordovician trimerellacean brachiopod shell beds"](https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1502-3931.1983.tb00659.x). *Lethaia*. **16** (3): 215–232. [Bibcode](/source/Bibcode_(identifier)):[1983Letha..16..215W](https://ui.adsabs.harvard.edu/abs/1983Letha..16..215W). [doi](/source/Doi_(identifier)):[10.1111/j.1502-3931.1983.tb00659.x](https://doi.org/10.1111%2Fj.1502-3931.1983.tb00659.x). [ISSN](/source/ISSN_(identifier)) [0024-1164](https://search.worldcat.org/issn/0024-1164).

1. ^ [***a***](#cite_ref-:0_4-0) [***b***](#cite_ref-:0_4-1) Popov, Leonid E.; Holmer, Lars E.; Bassett, Michael G.; Pour, Mansoureh Ghobadi; Percival, Ian G. (2013). Harper, D.A.T.; Servais, T. (eds.). ["Chapter 10: Biogeography of Ordovician linguliform and craniiform brachiopods"](https://doi.org/10.1144%2FM38.10). *Geological Society, London, Memoirs*. Early Palaeozoic Biogeography and Palaeogeography. **38** (1): 117–126. [doi](/source/Doi_(identifier)):[10.1144/M38.10](https://doi.org/10.1144%2FM38.10). [ISSN](/source/ISSN_(identifier)) [0435-4052](https://search.worldcat.org/issn/0435-4052).

1. ^ [***a***](#cite_ref-:1_5-0) [***b***](#cite_ref-:1_5-1) Curry, Gordon B.; Brunton, Howard C. (2007). ["Chapter 9: Stratigraphic Distribution of Brachiopods"](https://journals.ku.edu/InvertebratePaleo/article/view/5523/4996). In Selden, Paul A. (ed.). [*Part H, Brachiopoda (Revised). Volume 6: Supplement*](https://journals.ku.edu/InvertebratePaleo/issue/view/505). [Treatise on Invertebrate Paleontology](/source/Treatise_on_Invertebrate_Paleontology). Boulder, Colorado; Lawrence, Kansas: Geological Society of America; University of Kansas. pp. 2901–2965. [ISBN](/source/ISBN_(identifier)) [978-0-8137-3136-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8137-3136-0).

1. ^ [***a***](#cite_ref-:3_6-0) [***b***](#cite_ref-:3_6-1) Rong, Jiayu; Harper, D.A.T.; Huang, Bing; Li, Rongyu; Zhang, Xiaole; Chen, Di (2020). ["The latest Ordovician Hirnantian brachiopod faunas: New global insights"](https://linkinghub.elsevier.com/retrieve/pii/S0012825220303263). *Earth-Science Reviews*. **208** 103280. [Bibcode](/source/Bibcode_(identifier)):[2020ESRv..20803280R](https://ui.adsabs.harvard.edu/abs/2020ESRv..20803280R). [doi](/source/Doi_(identifier)):[10.1016/j.earscirev.2020.103280](https://doi.org/10.1016%2Fj.earscirev.2020.103280). [S2CID](/source/S2CID_(identifier)) [225549860](https://api.semanticscholar.org/CorpusID:225549860).

1. ^ [***a***](#cite_ref-:5_7-0) [***b***](#cite_ref-:5_7-1) Chen, Di; Huang, Bing; Candela, Yves (2023). ["Evolutionary trends in trimerellid brachiopods"](https://linkinghub.elsevier.com/retrieve/pii/S0031018223000901). *Palaeogeography, Palaeoclimatology, Palaeoecology*. **617** 111472. [Bibcode](/source/Bibcode_(identifier)):[2023PPP...61711472C](https://ui.adsabs.harvard.edu/abs/2023PPP...61711472C). [doi](/source/Doi_(identifier)):[10.1016/j.palaeo.2023.111472](https://doi.org/10.1016%2Fj.palaeo.2023.111472). [S2CID](/source/S2CID_(identifier)) [257371885](https://api.semanticscholar.org/CorpusID:257371885).

1. **[^](#cite_ref-:4_8-0)** Popov, Leonid E.; Holmer, Lars E. (2007). ["Chapter 4 (part): Trimerellida"](https://journals.ku.edu/InvertebratePaleo/article/view/5518/4991). In Selden, Paul A. (ed.). [*Part H, Brachiopoda (Revised). Volume 6: Supplement*](https://journals.ku.edu/InvertebratePaleo/issue/view/505). [Treatise on Invertebrate Paleontology](/source/Treatise_on_Invertebrate_Paleontology). Boulder, Colorado; Lawrence, Kansas: Geological Society of America; University of Kansas. pp. 2592–2594. [ISBN](/source/ISBN_(identifier)) [978-0-8137-3136-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8137-3136-0).

## Bibliography

- Modzalevskaya, Tatyana Lvovna (2003). "Silurian and Devonian brachiopods from Severnaya Zemlya" (Russian Arctic). *Geodiversitas* 25 (**1**). pp. 73–107.

v t e Brachiopod orders Linguliformea Lingulata †Acrotretida Lingulida †Siphonotretida †Paterinata Paterinida Craniiformea Craniata Craniida †Craniopsida †Trimerellida Rhynchonelliformea †Chileata Chileida Dictyonellida †Kutorginata Kutorginida †Obolellata Naukatida Obolellida Rhynchonellata †Athyridida †Atrypida †Orthida †Pentamerida †Protorthida Rhynchonellida †Spiriferida †Spiriferinida Terebratulida Thecideida †Strophomenata Billingsellida Orthotetida Productida Strophomenida

Taxon identifiers Trimerellida Wikidata: Q16907681 Wikispecies: Trimerellida EoL: 4342295 IRMNG: 10627 Open Tree of Life: 5301762 Paleobiology Database: 26591

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Adapted from the Wikipedia article [Trimerellida](https://en.wikipedia.org/wiki/Trimerellida) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Trimerellida?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.