Brachythyrididae, Fredericks, 1924
publication ID |
https://doi.org/ 10.4202/app.00972.2022 |
persistent identifier |
https://treatment.plazi.org/id/41708783-FFFF-FF92-8F42-CBDAFB1AFB1E |
treatment provided by |
Felipe |
scientific name |
Brachythyrididae |
status |
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Brachythyrididae View in CoL gen. et sp. indet.
Fig. 16E, F View Fig .
Material.—Two ventral valves: MPUM12049 (RCC11-8); MPUM12050 (RCC73-23i). Two dorsal valves: MPUM 12051 (RCC41-18a); MPUM12052 (RCC42-5a). All from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian, upper Visean.
Remarks.—Specimen MPUM12049 is a medium-sized suboval ventral valve with a wide cardinal margin, shallow sulcus and ornamentation of eight broad simple flat lateral costae with narrow interspaces, reaching a width up to 4.0 mm anteriorly, and two faint costae in the sulcus. The specimen is thus very close to L. rotundata , although it lacks the median furrow in the umbonal region; in fact, the sulcus seems to occur only anteriorly.
Specimen MPUM12052 is a fragment of a suboval flat dorsal valve with five to six simple, broadly rounded lateral costae extending from the umbo and a smooth low fold. The cardinal margin is not fully preserved, but it is inferred to be narrow, suggesting a possible assignment to Brachythyris ovalis ( Phillips, 1836) , a species that shows a gently convex dorsal valve and a smooth fold.
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