Lower and Midle Cambrian rhynchonelliform brachiopods from the Argentine Precordillera

JOURNAL OF PALEONTOLOGY

PALEONTOLOGICAL SOC INC

Lugar: Lawrence; Año: 2010

0022-3360

ABSTRACT—The first Cambrian rhynchonelliform brachiopods are described from the Precordillera mountain belt of west-central Argentina, including the new species Wimanella trimariae and Nisusia ancaucha. Other taxa described are Diraphora  cf. D. borealis (Walcott), Diraphora sp., and an indeterminate bohemiellid. Brachiopods come from the lowermost part of the Cambrian succession (El Estero Member of the La Laja Formation, Cerro Totora Formation) and from a resedimented huge block (Ancaucha olistolith) within the Los Sombreros olistostrome. The associated trilobites constrain the fossiliferous levels to the Bonnia-Olenellus and Poliella denticulata Biozones. A re-assessment of affinities of Lower and early Middle Cambrian rhynchonelliform brachiopods by using cluster analysis supports the existence of a widespread warm-water Tropical realm – to which the described Precordilleran faunas belong– and a more restricted ‘Mediterranean’ realm developed on the temperate, mixed clastic-carbonate platforms.