Ontogeny of the proetoid trilobite Stenoblepharum Owens, 1973, and the relationships of a new species from the Upper Ordovician of Argentina.

EDGECOMBE, G.D., B.D.E. CHATTERTON, N.E. VACCARI AND B.G. WAISFELD, 1997

JOURNAL OF PALEONTOLOGY

The Paleontological Society

Lugar: Lawrence, Kansas; Año: 1997 p. 419 - 433

0022-3360

Silicified material from Early Caradoc part of the Las Aguaditas Formation in San Juan Province, Argentina, includes a nearly complete growth series for a new species of the trpidocoryphid Stenoblepharum Owens, 1973. Cladistic analysis of Stenoblepharum speceis indicates that S. astinii new species is most closely allied to the early Caradoc S strasburgense (Cooper, 1953) from Virginia. Chinese species of Stenoblepharum are sister group to a Baltic/Laurentian clade. A single adult-like protaspid stage occurs in the life cycle of S. astinii, closely resembling the protaspis of Decoroproetus. It is preceded by a non-adult-like first protaspid instar that appears to the caracteristic of Proetoidea in general but contrast markedly with the early stages of the other taxa in Proetida.