Spisula, GRAY, 1837

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 : 12

SPISULA GRAY, 1837

FIG. 20

UCMP 410439 is provisionally referred to Spisula aff. Spi. eugenensis ( Clark, 1925) as it closely resembles this species in general outline. Spisula eugenensis from the Oligocene Eugene Formation in Oregon figured by Hickman (1969, pl. 4, fig. 13), with its broadly rounded, centrally-placed beak and moderately sloping anterior and posterior dorsal margins from the umbo, is nearly identical to the specimen figured here. In addition, the Tsm Caldecott Tunnel specimen show a slight anterior and posterior umbonal ridge that match well with Spi. eugenensis . The Eugene Formation (Oligocene) specimens and the Tsm Caldecott Tunnel (middle Miocene) specimen are very similar but are considered possibly distinct because of the difference in age.

Figures

Figure 20. Spisula aff. Spi. eugenensis from the Tsm Caldecott Tunnel fauna, right valve(?). Hypotype from UCMP locality IP13004, UCMP 410439.