GUADALUPIAN STAGE

lowest stage of the Late Permian Series of rock strata in the United States, defined on the basis of a prominent reef complex in the Guadalupe Mountains of Texas (the Permian period began about 286 million years ago and ended about 245 million years ago). The Guadalupian stage also serves as the world standard for the lower part of the Late Permian. In Guadalupian time the conditions in the Delaware Basin of southwestern Texas became favourable for the development of a rich benthonic (bottom-dwelling) fauna. Similarly, reef-forming organisms flourished, and a great calcareous reef, known as the Capitan Reef, developed about the margins of the basin. The Guadalupian is characterized by an upper zone of the fusulinid genus Parafusulina and a succeeding zone of Polydiexodina. Ammonoid zones include the Waagenoceras and the following Timorites.