THE PERMIAN CAPITAN LIMESTONE REEF AND THE MYTH OF SCIENTIFIC MATURITY

The Permian Reef Complex (Guadalupian) of West Texas and New Mexico is composed of the Goat Seep and overlying Capitan reef systems. Of these, the Capitan reef is arguably the best studied Permian reef in the world. Paleontological and paleoecological studies of the Capitan Limestone began nearly 150 years ago with the pioneering work of the Shumard brothers, and have been continued by an impressive array of geologists. The geological community is optimistically comfortable with the current understanding of the depositional geometry, paleontology, and paleoecology of this reef, even though we have experienced a number of significant paradigm shifts over the past 75 years. It is inescapable that the degree of outcrop accessibility has shaped and colored our perspectives of the depositional setting, paleoecology, and of the nature of the underlying paleontological communities responsible for construction of these reefs. The Upper Capitan reef is best known simply because the outcrops lie close to road systems and have relatively easy access. Progressively older sections of the Capitan reef, and the Goat Seep Reef itself, are less well known due to difficult access. Implicit in paradigm acceptance is the perception that the geological community understands the outcrops that have already been studied; a logical by-product of this perception is that the interpretations generated from these few outcrops can be extrapolated to the unstudied portions of the Capitan reef system. However, recent re-examinations of well-studied outcrops in New Mexico and West Texas have yielded a number of important paleontological and paleoecological advances. Among these are the discoveries of: (1) cryptic niches generated by meter-scale explanate sponges in the Upper Capitan reefs, (2) microbial involvement in the generation and preservation of micrite in the Middle Capitan reefs, and (3) sub-meter scale cryptic niches in the Middle Capitan reefs. Recent examinations of unstudied outcrops have resulted in discovery of new sponge species and framework architectures. New data and understandings have again modified the paradigm for the Capitan reef, and point out the dangers associated with extrapolating from a limited number of non-random outcrops and samples to the Capitan reef system as a whole.