Abstract: Early and Middle Cretaceous Hippuritacea (Rudists) of Gulf Coast

Alan H. Coogan

A rich and diverse Early and middle Cretaceous (Aptian-Cenomanian) rudist fauna of five stocks--the requieniids, monopleurids, caprotinids, radiolitids, and coalcomaninid caprinids--built the widespread and commonly thick bank and reef deposits of the Gulf Coast area including Mexico and the Caribbean islands.

Provincialism in the Early and middle Cretaceous fauna, especially among the coalcomaninid caprinids in the Western Hemisphere, limits the use of caprinid genera for interhemispheric correlation. Late Cretaceous (Turonian-Maestrichtian) provincialism is more pronounced in both hemispheres among the rudists involving caprinid, radiolitid, and hippuritid genera.

Biostratigraphically, the coalcomaninid caprinids are as useful for dating the Early and middle Cretaceous strata of the Western Hemisphere reef and bank facies as are the large arenaceous forams. Establishment of an interrelated stratigraphic framework based on surface and subsurface control allows the recognition of Aptian; early, middle, and late Albian; and Cenomanian stages determined by use of genera and species of rudists and arenaceous forams of the reef and bank facies.

Further biostratigraphic and paleontologic work is necessary to elucidate fully the composition of Early and middle Cretaceous rudist faunas. Nevertheless, at this time, morphologically distinct and widespread genera can be used.

AAPG Search and Discovery Article #90967©1977 GCAGS and GC Section SEPM 27th Annual Meeting, Austin, Texas