(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. (2008 a) 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. 2013 b) which appears to have finer, more numerous, and more closely spaces radial ribs than Lyriochlamys complexicostata (see Ascher 1906, pl. 14, fig. 1).