Runcinodiscus
| Runcinodiscus Temporal range: Late Botomian
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| Genus: | Runcinodiscus Rushton, 1976
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Runcinodiscus Rushton (in Bassett et al. 1976, p. 636-7) [1] is a genus of Lower Cambrian Eodiscinid trilobite belonging to the family Weymouthiidae (Kobayashi 1943),[2] Order Agnostida (Salter 1864).[3]
Type Species
[edit]By Monotypy and original designation, Runcinodiscus index Rushton (in Bassett et al. 1976). Holotype is A 15360 in the collection of the Sedgwick Museum of Earth Sciences, University of Cambridge.
Locality and age
[edit]The Type specimen (Cobbold, 1931) was collected from the Protolenus Limestone (Ac5) [Comley Series], 180m south of Comley Quarry, near Church Stretton, Shropshire, England - grid reference SO 4849 9625 according to Morris (1988, p.205).[4]
Remarks
[edit]Fletcher & Theokritoff (2008) [5] designated Shaw’s (1950, pl. 79, fig. 24) [6] specimen of “ Weymouthia nobilis (Ford, 1872)” [7] as the holotype of a new species, Serrodiscus weymouthioides, and considered Runcinodiscus Rushton (in Bassett et al., 1976) [= ?Weymouthia nobilis (Ford, 1872)] to be a junior synonym of Serrodiscus; Rushton (1976) had previously regarded Weymouthia and Runcinodiscus as closely allied with Serrodiscus. Weymouthia nobilis (Ford 1872), first described from the Taconic region of New York State, was also recorded by Cobbold (1931) from the Protolenus Limestone (Ac5) [Protolenid-Strenuellid Zone] at Comley, Shropshire, England,[8] but Rushton (in Bassett et al., 1976, p. 637) showed that the English specimens are specifically distinct from W. nobilis as described by Ford (1872) and, with some reservation, erected new genus and species, Runcinodiscus index.
Runcinodiscus cf. index Rushton, described originally by Kiær (1917) as Weymouthia nobilis,[9] was recovered from the Lower Cambrian Holmia Shale (Holmia Kjerulfi Assemblage-zone) at Tømten, close to Lake Mjøsa, Southeast Norway (Ahlberg, 1983, p. 289, fig. 1).[10]
References
[edit]- ^ BASSETT M. G., OWENS R. M., and RUSHTON A. W. A. 1976. Lower Cambrian fossils from the Hell’s Mouth Grits, Journal of the Geological Society 132 (6): 623–644. http://pubs.geoscienceworld.org/jgs/article-pdf/132/6/623/4885552/gsjgs.132.6.0623.pdf
- ^ KOBAYASHI T. 1943. Brief notes on the Eodiscids 1, their classification with a description of a new species and a new variety, Proceedings of the Imperial Academy, Tokyo, Volume 19, pp. 37-42.
- ^ SALTER, J. W. 1864: On some new fossils from the Lingula - flags of Wales. Quarterly Journal of the Geological Society of London, 20, 233–241.
- ^ MORRIS, S. F. 1988. A review of British trilobites, including a synoptic revision of Salter's monograph. Palaeontogr. Soc. (Monogr.), 1-316. pp. 26, 255.
- ^ FLETCHER, T. P. & THEOKRITOFF, G., 2008. The Early Cambrian of eastern Massachusetts. Northeastern Geology and Environmental Science, 30, 301-329.
- ^ SHAW, A. B., 1950. A revision of several Early Cambrian trilobites from eastern Massachusetts. Journal of Paleontology, 24, 577-590.
- ^ FORD, S. W., 1872. Descriptions of some new species of primordial fossils. American Journal of Science, Series 3, 3, 419-422.
- ^ COBBOLD, E. S. 1931. Additional fossils from the Cambrian rocks of Comley, Shropshire. Q. J. Geo/. Soc. Lond. 87, 459 - 511.
- ^ KIÆR, J. 1917. The Lower Cambrian Holmia fauna at Tømten in Norway. Skr. Nor. Videnskapsselsk., l. Mat.-Naturvidensk. Kl. 1916, (10), 140 pp.
- ^ AHLBERG, P. 1983. Redescription of a Lower Cambrian eodiscid trilobites from Norway. Norsk Geologisk Tidsskrift, Vol. 63, pp. 289 - 290. Oslo.