CONODONT FAUNA FROM THE ROTELLIFORME, MEEKI AND OCCIDENTALIS ZONES (MIDDLE TRIASSIC) OF HUMBOLDT RANGE, NEVADA, WESTERN-NORTH AMERICA

Abstract

The conodont fauna of the Rotelliforme, Meeki, Occidentalis and lower Subasperum zones of Nevada (Humboldt Range) is here described. The first three zones represent, by means of the American authors, the Upper Anisian of North America, while at the base of the Subasperum Zone is located the Anisian/Ladinian boundary. Three species—groups of conodonts have been emended and revised, they are: Gondolella constricta Mosher & Clark, Gondolella mombergensis mombergensis Tatge and Gondolella mombergensis longa (Budurov & Stefanov). Comparisons with the possible coeval faunas of epicontinental sequences from Europe have been discussed. Within the conodont fauna, the main change has been noted at the base of the Occidentalis Zone. On the base of the conodont fauna, the Anisian/ Ladinian boundary at the base of the Occidentalis Zone seems to be the most supported in Nevada.