Lyriochlamys complexicostata ( Gabb, 1869 )

Kaim, Andrzej, Jenkins, Robert G., Tanabe, Kazushige & Kiel, Steffen, 2014, Mollusks from late Mesozoic seep deposits, chiefly in California, Zootaxa 3861 (5), pp. 401-440 : 426-427

Lyriochlamys complexicostata ( Gabb, 1869)

( Fig. 14 )

Pecten complexicostata Gabb, 1869 , p. 199, pl. 33, fig. 97.

Pecten complexicostata Gabb—Stanton 1895 , p. 37–38, pl. 2, figs. 7–9.

Material and occurrence. Six specimens from Rocky Creek (probably Valanginian, Early Cretaceous), up to 68 mm in height. Stanton’s (1895) figured specimens ( USNM 23028 and 23102) were not found in the USNM type collection during a visit in November 2012, but many specimens from Hauterivian (Early Cretaceous) Wilbur Springs seep site (which is located near the Bear Creek seep site reported here; see description of locality # 5 in Kiel et al. (2008a) for details) were seen in the non-type collection.

Remarks. Gabb’s (1869) specimens are from ‘Morgan Valley south of Clear Lake’ ( Stanton 1895, p. 37), which is a wide area that also encompasses the Rocky Creek site where the present material was collected. Stanton’s (1895) specimens are from Wilbur Springs, thus the species is widely distributed among Early Cretaceous seep deposits in California. Both at Rocky Creek and at Wilbur Springs the specimens occur in clusters in which several specimens were stacked upon each other in random orientation. At Wilbur Springs they were also closely associated with the brachiopod Peregrinella whitneyi . Other pectinids at Cretaceous seep deposits include a rare Propeamussium at the Early Cretaceous seeps deposits in the Kuhnpasset beds in Greenland ( Kelly et al. 2000) and a rare ‘ Pecten sp.’ at the potential seep site ‘Koniakauer Schloß’ in Czech Republic ( Ascher 1906, cf. Kiel & Peckmann 2008, Kaim et al. 2013b) which appears to have finer, more numerous, and more closely spaces radial ribs than Lyriochlamys complexicostata (see Ascher 1906, pl. 14, fig. 1).

Figures

FIGURE 14. Lyriochlamys complexicostata (Gabb, 1869) from Cretaceous seep carbonates in California, showing various stages of defoliation; all specimens from Hauterivian of Wilbur Springs except for that in fig B, which are from Rocky Creek (probably Valanginian). A. Small specimen with fine radial sculpture (USNM 597562). B. Large specimen in whom the main ribs appear sharp, note fragments of the same species on the far and lower left (GZG. INV. 85002). C. Specimen with almost no shell preserved (USNM 597563). D. Specimen with fine radial ribs and rough commarginal wrinkles on the ears (USNM 597564). E. specimen in which the main ribs appear blunt (USNM 605206). F. Specimen with blunt vertical ribs on the ear; note abundant fragments of the brachiopod Peregrinella whiteyi at the lower side (USNM 597565).