Assessing the biodiversity of ordovician ostracods from the Argentine Precordillera

SALAS, MARIA JOSE

JOURNAL OF PALEONTOLOGY

The Paleontological Society

Lugar: Lawrence, Kansas; Año: 2007 vol. 81 p. 1442 - 1453

0022-3360

Ostracod faunas from the Lower to Middle Ordovician rocks of the Argentine Precordillera Basin (Gualcamayo and Las Aguaditas Formations) are studied. A new family Garcianidae n. fam. is erected. One new genus, Jeanvannieria n. gen., and six species are recognized, two of which are new (Jachalipisthia bicornata n. sp., and Jeanvannieria bulbosa n. gen. and sp.). The diversity and composition of the Precordilleran ostracods is evaluate in base of previous taxonomic analysis and the fauna studied here. The diversity is moderate, with a peak of 50 species during the early Caradoc. The composition of the fauna is characterized by the dominance of Podocopes with a high percentage of binodicopes, and the lack of Palaeocopes which is in agreement with a deep shelf environment. The carbonate slope setting of the Las Aguaditas Formation is the deepest environment, yet found, with Ordovician ostracods and records a relatively highly diverse fauna. The presence in Precordillera of Ectoprimitioides suggest biogeographic affinities between Precordillera and Laurentia. The rest of the fauna has a high percentage of endemic genera, and a mixture of genera with several affinities, Baltic, peri-Gondwanan, and Australian.