Sponges and chancelloriids from the Cambrian of western Argentina

Abstract

Anthaspidellid sponges are reported from the La Laja Formation in the Chica de Zonda Range in the Precordillera Oriental, Argentina. These are generically unidentifiable fragments of trabs and more or less well-defined dendroclone spicules. They occur as skeletal elements in small transported fragments and are the only Cambrian occurrence of anthaspidellids known thus far from South America.Walcott (1920) proposed to include an array of dissociated spicules, including triradiate prodiaenes, hexactines, and probable monactine spicules, in the genus Kiwetinokia. Assemblages tentatively identified as Kiwetinokia utahensis? Walcott, 1920, are reported from the Estancia San Martin Formation, of latest Early Cambrian and early Middle Cambrian age from San Isidro Gulch near Mendoza. Similar spicule assemblages occur in the La Laja Formation from the Chica de Zonda Range, in the Precordillera Oriental near San Juan, and in the Los Sombreros Formation in the Tontal Range of the Precordillera Occidental.Sclerites of the sponge-like Chancelloria eros Walcott, 1920, are described from the upper Lower to lower Middle Cambrian La Laja Formation. Chancelloria sclerites are also reported here from rocks of the Middle Cambrian Glossopleura Zone in the San Isidro Formation in Empozada Gulch in the San Isidro area of the Precordillera Austral, west of Mendoza, in Mendoza Province. Sponges and chancelloriids from the Cambrian of Argentina are known basically from dissociated skeletal elements.