Adductor Scar on the Shells of the Early Cambrian Species Sinskolutella ordinata (Melnikova, 1983) (Bradoriida, Crustacea)

In bradoriids Sinskolutella ordinata (Melnikova, 1983) from the unique Sinsk locality (Lower Cambrian of the Siberian Platform), a large round spot was found in the anterior half of the shell, identified as the adductor muscle scar. Additional characteristics of the pores on the valves of this species are described. Similarities in the outline, shell size, and development of a large muscle scar suggest that sinskolutellas are related to ostracods of the order Leperditicopida, known from the Ordovician and widely diversified during the Silurian and Devonian.