UGA Stratigraphy Lab

The data is in the strata



Superfamily Stephanoceratoidea

Family Stephanoceratidae: Evolute, planulate, ribbed, with tubercles and branching ribs.

Family Otoitidae: Evolute, strong primary ribs that bifurcate, with subdued tubercles.

Family Kosmoceratidae: Round whorled, mesovolute (Kepplerites) to evolute (Kosmoceras), with branching ribs

Family Sphaeroceratidae: Sphaerocones and cadicones (very wide and squat); involute and highly inflated inner whorls. Ribs persist to end of growth. Dimorphs differ only in size.

Family Cardioceratidae: Commonly dimorphic. Wide variation in shell inflation.

Superfamily Spiroceratoidea

Family Spiroceratidae: Openly coiled, becoming loosely curved or straight, strongly ribbed.

Superfamily Perisphinctoidea

Family Perisphinctidae: Evolute and planulate, with ribbing that splits towards venter, not keeled.