The ontogeny of the species Conchoprimitia osekensis (Přibyl, 1979) from the Šárka Formation (lower and middle Darriwilian) is evaluated. Eight ontogenetic stages (A-8 to A-1) and one adult specimen are described and illustrated.
This study displays that another common species of the same stratigraphical unit, Conchoprimitia? dejvicensis Přibyl, 1979, represents early instars of C. osekensis. It clearly demonstrates the importance of such ontogenetic studies for understanding real taxonomy and diversity of fossil ostracods.