Trilobites from theCedaria prolificaZone (Cambrian, upper Guzhangian) of the Precordillera of Mendoza, western Argentina

Abstract

AbstractTrilobites from the upper Guzhangian of the southern Argentine Precordillera, preliminarily described by Carlos Rusconi in the 1950s, are revised herein. The specimens studied were collected from an allochthonous limestone block of La Cruz Olistoliths at 200 m northwest of Estancia San Isidro locality (San Isidro area, Mendoza). Taxa compriseKormagnostus seclusus(Walcott, 1884),Cedaria prolificaWalcott, 1924,C.puelchanaRusconi, 1954,Tricrepicephalus texanus(Shumard, 1861),Meteoraspis metra(Walcott, 1890),Coosia conicephala(Rusconi, 1954) new combination,Coosella texana? Resser, 1942,Nasocephaluscf.N. nasutusWilson, 1954, andOlenoides proa(Rusconi, 1954) new combination. The North American generaMeteoraspisResser, 1935 andNasocephalusWilson, 1954 are reported confidently from South America for the first time. This assemblage is representative of theCedaria prolificaZone, which correlates with the lowerCrepicephalusZone of the traditional North American genus-based zonation. Most of the genera and species identified were previously described exclusively from Canada, the United States, and northwestern Mexico, a fact that provides new support to an allochthonous Laurentian origin of the Argentine Precordillera.