Triarthrinid trilobites (Olenidae) from the Middle and Upper Ordovician, Precordillera of Argentina.

EDGECOMBE, G., B. D. E. CHATTERTON, N. E. VACCARI, Y B. G. WAISFELD, 2005.

JOURNAL OF PALEONTOLOGY

The Paleontological Society

Lugar: Lawrence-Kansas; Año: 2005 vol. 79 p. 89 - 109

0022-3360

Middle and Upper Ordovician Triarthrinae from the Precordillera of San Juan, Argentina, include the Whiterock/Llanvirn Porterfieldia turneri (Baldis and Po¨the, 1995) and P. acava new species, and the early Caradoc Triarthrus jachalensis (Harrington and Leanza, 1957). Each of these species is described based on silicified material, including ontogenies, from the Las Aguaditas Formation. Porterfieldia maanssonae new species from the lower member of the Gualcamayo Formation (late Arenig) at Rý´o Gualcamayo, San Juan Province, and Río Guandacol, La Rioja Province, is closely allied to P. turneri. Two protaspid stages are present in Porterfieldia, whereas mineralized protaspid stages are apparently lacking in Triarthrus jachalensis. Triarthrus jachalensis was capable of sphaeroidal enrollment by meraspid degree 2. Precordilleran species bear closest comparison to others from Spitsbergen (Porterfieldia acava n. sp. and P. parapunctata) and Sweden/Norway (Triarthrus jachalensis and T. linnarssoni).