Middle Cambrian trilobites from the vicinity of Dolgii Mys Mountain (Khakassia, Batenevsky Ridge)

Abstract

The trilobites Oryctocarella sibirica (Tomash.) and Lancastria plana (Tomash.) from the basal Middle Cambrian in the vicinity of Dolgii Mys Mountain (Batenevsky Ridge, Khakassia) are described. These trilobites were previously described by V.D. Tomashpolskaya, but the original collection was subsequently lost. Repeated finds allowed a detailed study of these species. It is established that relatively small specimens of Oryctocarella sibirica are more similar to Ovatoryctocara granulata. In addition, these species have much in common with the genus Arthricocephalus in morphological characters. New material of Lancastria plana is described in detail. These trilobites were originally assigned to the genus Paraoryctocephalops, although according to the data of Blacker and Peel (1997), they should be transfered to the genus Lancastria.