New raphiophorid trilobites from the Ordovician of Argentina and their biogeographic implications.

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

Memoir of the Association of Australasian Palaeontologists

Association of Austrlasian Paleontologists

Lugar: Sydney; Año: 2006 p. 353 - 374

0810-8889

The raphiophorid trilobites Lehnertia nawisapa gen. et sp. nov. and Pytine wirayasqa sp. nov. are described from the Lower and Middle Ordovician of Argentina. Lehnertia gen. nov. is a member of Endymioniinae that includes L. nawisapa, from the Las Chacritas Formation (Darriwilian) in the Precordillera of San Juan Province, and L. embolion, from the Nora Formation (Darriwilian)in the Georgina Basin, Australia. An extension of the cephalic doublure as a long, pointed spine in Lehnertia is regarded as convergent with a similar spine in Alsataspididae. Silicified material of L. nawisapa includes a growth series from protaspides to holaspides, recording the development of the ocular structures and an increase in the relative size of the eyes late in ontogeny. Lehnertia is most closely allied to Pytine Fortey, 1975; both genera include species with and without ocular structures. Pytine wirayasqa sp. nov. is found in the Acoite Formation (early Arenig) in the Cordillera Oriental, Jujuy Province. In addition to its type from Spitsbergen and the new species from Argentina, Pytine includes early Arenig-Darriwilian species from the North and South China blocks, Baltica, and East Gondwana (Canning Basin, Australia). Lehnertia provides further evidence for East Gondwanan influence on Precordilleran faunas in the Darriwilian. A reevaluation of the trilobite fauna of the Cordillera Oriental suggests East Gondwanan connections since the Early Tremadocian.