The Cretaceous carbonate platforms of the Americas and their rudist bivalves

Abstract

Following the breakup of Pangaea, many rifted margins of the Americas became carbonate platforms. During the Cretaceous, these platforms, as well as those associated with volcanic arcs, were populated by rudist bivalves that underwent a major radiation from the Early to Late Cretaceous. Carbonate platform development was episodic with major platforms represented by the Hauterivian to early Aptian, the early to late Albian and the Campanian to Maastrichtian. Different rudist bivalves characterised different phases of platform development. The Hauterivian to Aptian saw the rise of the Rethinae and Caprinidae, and was terminated by OAE1a. The Albian saw the rise of the Caprinuloideina and Youngicaprininae together with the first radiolitids. The Cenomanian is poorly understood in term of rudist bivalve development and the effects of the C-T boundary event (OAE2) are not well documented in the Americas. The Turonian to Maastrichtian saw a major radiation at the genus level of the rudists - hippuritids were initially represented by cosmopolitan genera, but through the late Santonian to early Campanian these were replaced by endemic genera. The radiolitids and antillocaprinids also underwent major radiations at this time, and numerous new endemic taxa characterised the carbonate platforms of the Americas. The Cretaceous-Paleogene boundary event decimated the carbonate platforms of the Americas and wiped out the rudist bivalves. Two new radiolitid genera are described: Vermuntia and Thiadensia .