Clypeaster cotteaui

Phylum Echinodermata
Class Echinoidea
Order Clypeasteroida

(Scale bar is 1 cm)

 

One of two common species of Clypeaster in lower Oligocene rocks, this one is easily recognized by its strongly concave oral surface (upper photo at left) C. rogersi has a nearly flat bottom, in contrast. The two species usually occur in different beds even when they are found at the same locality.

In this respect they are like the two modern species of the genus that live in the Caribbean region: C. subdepressus and C. rosaceus which live in different ways. The former is relatively flattened (like C. rogersi) and lives buried shallowly in sandy bottoms. The latter is more inflated (like C. cotteaui) and lives at the surface of the sediment rather than within it.

Though the morphology of the test of C. cotteaui suggests that it might have been able to burrow to shallow depths in coarse sediment, it is most commonly found with sediment through which it would have been unlikely to have burrowed at all, such as the rhodolith-rich facies of the Bridgeboro Limestone.

The species is known only from lower Oligocene (Vicksburgian or Rupelian) rocks in Georgia and Alabama, including the Bridgeboro Limestone and the undifferentiated Oligocene residuum of the Dougherty Plain. It also occurs in Cuba.

AGE: EARLY OLIGOCENE

FORMATION: BRIDGEBORO LIMESTONE and RESIDUUM

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