(Scale bar in both photos is 1 cm.)

Prionocidaris mortoni

Phylum Echinodermata
Class Echinoidea
Order Cidaroida

This species is the most common regular echinoid in the region. Most often the shell is found in a partial state, with one double row of tubercles and half the pore rows on either side of it (approximately the middle third of the photo above left). The spines attributed to this species are rather large and ornamented with a row of coarse thorns down each side, as shown in the photo above right. These are often found individually.

Prionocidaris mortoni is restricted to the Ocala Limestone in Georgia, but similar species are commonly found in Oligocene rocks and less commonly in other age rocks.

The species lived at the sediment surface, as do its living relatives, and like those relatives it is found in a variety of different sediment types.


AGE: LATE EOCENE

FORMATION: OCALA LIMESTONE

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