Cambrian trilobites from the Glossopleura walcotti Zone (Miaolingian Series, Wuliuan Stage) of Mendoza, western Argentina

Abstract

The Museo de La Plata houses numerous Miaolingian and Furongian fossils from the southern Precordillera of Mendoza, western Argentina, collected by Ángel V. Borrello during the 1960s. Early Miaolingian (Wuliuan) trilobites from these collections are described herein. The specimens studied come from allochthonous limestone blocks (San Isidro Olistoliths) of key fossiliferous localities of the San Isidro area (Cerro Martillo, Quebrada Oblicua, Quebrada Empozada, Quebrada San Isidro). Taxa comprise Athabaskia anax (Walcott), Glossopleura leona Lochman, Kootenia aff. K. incerta (Rusconi), Kootenia crassa Fritz, Oryctocephalites reynoldsi (Reed), Zacanthoides sp., Spencia? sp., Amecephalus normale? (Resser), Amecephalus laticaudum? (Resser), and Amecephalus sp. This assemblage is representative of the North American Glossopleura walcotti Zone, and closely allied to faunas from the Great Basin (Spence Shale), Sonora, and to a lesser extent from northwestern Idaho.

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

“…Cedaria prolifica Walcott, 1924 is the most abundant species in the fauna studied and provides precise age information as it is known from the eponymous zone of northwest Canada, as well as from the partially equivalent Crepicephalus Zone of British Columbia, Alabama, and Tennessee (Resser, 1938; donaro et al, 1993 andTortello, 2022). The 200 m northwest of Estancia San Isidro locality is indicated by an asterisk.…”

“…Recent systematic revisions of the Rusconi collections provided updated information on several standard North American trilobite zones such as the Glossopleura walcotti , Ehmaniella , Lejopyge laevigata , Elvinia and Saukia zones (Tortello and Bordonaro, 1997; Bordonaro, 2003, 2014; Bordonaro and Fojo, 2011; Pratt and Bordonaro, 2014; Tortello, 2018, 2020, 2022).

Figure 1.Map of the San Isidro area, Mendoza Province, Argentina (after Bordonaro et al, 1993 and Tortello, 2022). The 200 m northwest of Estancia San Isidro locality is indicated by an asterisk.

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“…Map of the San Isidro area, Mendoza Province, Argentina (after Bordonaro et al, 1993 and Tortello, 2022). The 200 m northwest of Estancia San Isidro locality is indicated by an asterisk.…”

“…It is now recognized that Cambrian trilobites from the Argentinian Precordillera have clear Laurentian affinities. Recent systematic revisions of the Rusconi collections provided updated information on several standard North American trilobite zones such as the Glossopleura walcotti, Ehmaniella, Lejopyge laevigata, Elvinia and Saukia zones (Tortello and Bordonaro, 1997;Bordonaro, 2003Bordonaro, , 2014Bordonaro and Fojo, 2011;Pratt and Bordonaro, 2014;Tortello, 2018Tortello, , 2020Tortello, , 2022.…”