Dalmanellidae

Dalmanella testudinaria, copyright TalTech Geoloogia Instituut.
Belongs within: Enteletida.
Uncertain Dalmanella
Published 26 December 2018

The photo above (copyright Dave), may or may not show Dalmanella, a brachiopod originally described from the later Ordovician of Sweden. Dalmanella belongs to the Orthida, one of the earliest groups of articulate brachiopods to appear in the fossil record (‘articulate’ meaning that the two valves of the shell are hinged together, not that they are particularly well spoken). The Dalmanellidae, the family to which Dalmanella belongs, are known from the lower Ordovician to the lower Carboniferous (Williams & Wright 1965).

Over the years, numerous fossil brachiopods from Europe and North America have been assigned to Dalmanella, leading Jin & Bergström (2010) to describe it as “perhaps one of the most commonly reported orthide brachiopods”. However, if truth be told, the main reason Dalmanella is so widely recognised is because of how perfectly unremarkable it is. It is small and unspecialised, and the genera within Dalmanellidae have mostly been separated by somewhat vague characters such as shell shape and ribbing pattern. Some studies of variation in dalmanellid populations have questioned whether characters used to separate genera can even be used to separate species or whether they may vary within a single population.

This uncertainty lead Jin & Bergström (2010) to restudy the original type species of Dalmanella, D. testudinaria. Their conclusion was that D. testudinaria was morphologically distinct from North American species attributed to the genus: for instance, the midline of the dorsal valve bore an interspace (the furrow between two costae) in D. testudinaria but a raised costa in the American species. The myophore, a process associated with the hinge to which the muscles responsible for opening the shell would have attached in life, is much narrower in D. testudinaria than in the American species. Not only were the morphologically distinct, they were ecologically distinct as well: D. testudinaria being found in cooler, deeper waters while the American species basked in tropical shallows. Not for the first time, it appears that an external sameyness masks an internal divergence.

Systematics of Dalmanellidae
Dalmanellidae [Dalmanellinae, Isorthinae, Onniellidae, Wattsellidae]WW65
|--+--Heterorthina Bancroft 1928B75, WW65 [incl. Bekkerella Rosenstein 1943 non Reed 1936WW65, Elsaella Alichova 1960WW65]
| | |--*H. praeculta Bancroft 1928WW65
| | `--*Bekkerella’ bekkeri Rosenstein 1943 [=*Elsaella bekkeri]WW65
| `--Levenea Schuchert & Cooper 1931B75, WW65 [incl. Dalmanellopsis Khalfin 1948WW65]
| |--*L. subcarinata (Hall 1857) [=Orthis subcarinata]WW65
| `--*Dalmanellopsis’ septiger Khalfin 1948WW65
|--Dalmanella Hall & Clarke 1892B75, WW65 [incl. Nocturnellia Havlíček 1950WW65, Wattsella Bancroft 1928WW65]
| |--*D. testudinaria (Dalman 1828)WW65 [=Orthis testudinariaWW65, Wattsella testudinariaSC31]
| |--D. canaliculata [=Orthis (Dalmanella) canaliculata]C01
| |--D. elementaria Williams 1974HB93
| |--D. fascicularisB75
| |--D. frechiG31
| |--D. indicaG31
| |--‘Orthis’ nocturna Barrande 1879 [=*Nocturnellia nocturna]WW65
| |--D. subquadrataG31
| `--D. wattsi (Bancroft 1928) [=*Wattsella wattsi]WW65
|--+--Isorthis Kozlowski 1929B75, WW65
| | |--*I. szajnochai (Kozlowski 1929) [=Dalmanella (*Isorthis) szajnochai]WW65
| | `--I. allaniH79
| `--+--ProtocortezorthisB75
| |--CortezorthisB75
| | |--C. bathurstensisN79
| | `--C. cortezensisN79
| `--+--Reeftonia Allan 1947B75, WW65
| | `--*R. marwicki Allan 1947WW65
| `--Cariniferella Schuchert & Cooper 1931B75, WW65
| `--*C. carinata (Hall 1843) [=Orthis carinata]WW65
`--+--Dedzetina Havlíček 1950B75, WW65
| `--*D. macrostomoides (Havlíček 1950) [=Parmorthis (*Dedzetina) macrostomoides]WW65
|--MystrophoridaeHB93
| |--VisbyellaB75
| |--Biernatium emanuelensis (Veevers 1959)HB93
| `--Mystrophora Kayser 1871WW65
| `--*M. areola (Quenstedt 1871) [=Orthis areola]WW65
`--+--Fascicostella Schuchert & Cooper 1931B75, WW65
| `--*F. gervilii (Defrance 1827)WW65 [=Strophomenes gerviliiWW65, Orthis gervilleiSC31]
`--Resserella Bancroft 1928B75, WW65 [incl. Parmorthis Schuchert & Cooper 1931WW65]
|--*R. canalis (Sowerby in Murchison 1839) [=Orthis canalis]WW65
`--R. elegantula (Dalman 1828) [=Orthis elegantula, *Parmorthis elegantula]WW65

Dalmanellidae incertae sedis:
Bancroftina Sinclair 1946 [=Raymondella Whittington 1938 non Reed 1935]WW65
`--*B. typa (Whittington 1938) [=*Raymondella typa]WW65
Eremotrema Cooper 1956WW65
`--*E. biconvexum Cooper 1956WW65
Cryptothyris Bancroft 1945 [incl. Crassiorina Havlíček 1950]WW65
|--*C. paracyclica (Bancroft 1928) [=Resserella paracyclica]WW65
`--*Crassiorina’ crassior (Barrande 1879) [=Orthis notata var. crassior]WW65
Paucicrura Cooper 1956 [incl. Cristiferina Cooper 1956]WW65
|--*P. rogata (Sardeson 1892)WW65 [=Orthis rogataWW65, Dalmanella rogataSC31]
`--*Cristiferina’ cristata Cooper 1956WW65
Howellites Bancroft 1945 [incl. Mesodalmanella Havlíček 1950]WW65
|--*H. striata (Bancroft 1945) [=Resserella (*Howellites) striata]WW65
|--H. antiquiorWW65
`--*Mesodalmanella’ flava Havlíček 1950WW65
Onniella Bancroft 1928 [incl. Soudleyella Bancroft 1945]WW65
|--*O. broeggeri Bancroft 1928WW65
|--O. grandisWW65
`--*Soudleyella’ soudleyensis Bancroft 1945WW65

*Type species of generic name indicated

References

[B75] Boucot, A. J. 1975. Evolution and Extinction Rate Controls. Elsevier Scientific Publishing Company.

[C01] Chapman, F. 1901. On some fossils of Wenlock age from Mulde, near Klinteberg, Gotland; with notes by Prof. T. Rupert Jones and Dr. F. A. Bather. Annals and Magazine of Natural History, series 7, 7: 141–160, pl. 3.

[G31] Grabau, A. W. 1931. The Permian of Mongolia: A report on the Permian fauna of the Jisu Honguer limestone of Mongolia and its relations to the Permian of other parts of the world. American Museum of Natural History: New York.

[HB93] Harper, D. A. T., C. H. C. Brunton, L. R. M. Cocks, P. Copper, E. N. Doyle, A. L. Jeffrey, E. F. Owen, M. A. Parkes, L. E. Popov & C. D. Prosser. 1993. Brachiopoda. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 427–462. Chapman & Hall: London.

[H79] House, M. R. 1979. Devonian in the Eastern Hemisphere. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A183-A217. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Jin, J., & J. Bergström. 2010. True Dalmanella and taxonomic implications for some Late Ordovician dalmanellid brachiopods from North America. GFF 132 (1): 13–24.

[N79] Norris, A. W. 1979. Devonian in the Western Hemisphere. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A218–A253. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[SC31] Schuchert, C., & G. A. Cooper. 1931. Synopsis of the brachiopod genera of the suborders Orthoidea and Pentameroidea, with notes on the Telotremata. American Journal of Science, Fifth Series 22 (129): 241–251.

[WW65] Williams, A., & A. D. Wright. 1965. Orthida. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt H. Brachiopoda vol. 1 pp. H299–H359. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas Press: Lawrence (Kansas).

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