CARDITIDAE FLEMING, 1828

Charles L. Powell, Ii, Clites, Erica C. & Poust, Ashley W., 2019, Miocene marine macropaleontology of the fourth bore Caldecott Tunnel excavation, Berkeley Hills, Oakland, California, USA, PaleoBios 36, pp. 1-34 : 10

CARDITIDAE FLEMING, 1828

FIG. 16

One indeterminate Cyclocardia has been recovered from the Caldecott Tunnel. It shows the exterior of a right(?) valve that has been crushed but appears to show greater than 16 broadly rounded radial ribs with slightly narrower shallow interspaces and appears to be crossed by fine co-marginal growth lines. This specimen is about 8.7 mm long and 7.5 mm high.

Only two Cyclocardia have been reported from the Miocene of California, Cy. monilicosta ( Gabb, 1861) [= Cy.occidentalis ( Conrad, 1855) ] and Cy. californica ( Dall, 1903) . According to its original description Cy. monilicosta was described from the Santa Barbara area and questionably referred to the Miocene. The Santa Barbara Formation, from which Cy. monilicosta was likely collected, is middle Pleistocene in age (Minor et al. 2002, 2009), although in the past the Santa Barbara Formation has been referred to rocks of Miocene to Pleistocene age ( Gabb 1861, Arnold and Arnold 1902, Moore 1983). Powell et al. (2010, p. 23, footnote) noted a single collection of Pliocene age from the Santa Barbara area and Minor et al. (2002, 2009) reported two geologic units of questionable Pliocene age in the sea cliffs below More Mesa just south of UC Santa Barbara at Goleta, so Pliocene but no Miocene geologic units occur in the area. Although it is uncertain which world oceans and is of no ecological significance here.

Figures

Figure 16. Cyclocardia sp. Indeterminate from the Tsm Caldecott Tunnel fauna, right valve(?). Hypotype from UCMP locality IP13001, UCMP 410563.