Yoldia, MOLLER, 1842

Charles L. Powell, Ii, Clites, Erica C. & Poust, Ashley W., 2022, Miocene marine macropaleontology of the fourth bore Caldecott Tunnel excavation, Berkeley Hills, Oakland, California, USA, PaleoBios 36, pp. 1-34 : 7

YOLDIA MÖLLER, 1842

FIGS. 6 , 7

Specimens are here referred to three taxa of the Yoldiidae . The largest specimens have a centrally-placed umbo and strong co-marginal sculpture, characters shared with the taxon Yoldia cf. Y. submontereyensis Arnold, 1908 ( Figs. 6 , 7). Yoldia submontereyensis has been previously reported from the upper part of the Temblor Formation (Loel and Corey 1932) and unnamed Miocene sandstone near Stanford University of Dibblee (1966). The second is typically smaller with the umbo placed slightly anterior of the middle of the shell, a more inflated anterior-dorsal margin, coarser co-marginal sculpture, and a truncated and inclined posterior end. Specimens with these characters are here identified as Yoldia cf. Y.supramontereyensis Arnold, 1908 ( Fig. 8 ). This species occurs in California from the Hambre Sandstone ( Hall 1958), “Monterey” Formation (Lutz 1951, Addicott et al. 1978), Oursan and San Ramon sandstones (Weaver 1953), Sobrante Sandstone (Lutz 1951), Temblor Formation (Stewart 1946), and unnamed sandstone near Stanford University of Dibblee (1966). The last species is only represented by a single partially covered specimen that cannot be identified to either genus or species with confidence and is referred here to Yoldia ? sp. indeterminate ( Fig. 9). It is easily distinguished from the previous two species by its much finer and more numerous co-marginal sculpture.

Figures

Figure 6. Yoldia cf. Y. submontereyensis from the Tsm Caldecott Tunnel fauna, left valve. Hypotype from UCMP locality IP13008, UCMP 218804.

Figure 8. Yoldia cf. Y. supramonterensis from the Tsm Caldecott Tunnel fauna, left valve. Hypotype from UCMP locality IP13003, UCMP 218714.