Abadiella, and the close-knit group of the families Estaingiidae, Ichangiidae and Ellipsocephalidae. Genera assigned to the Emuellidae Holyoakia has previously been assigned to the Emuellidae. The tailshiel (or pygidium) in Holyoakia is about the same size as its cranidium, with a well-defined axis, eight axial rings, well-developed pleural ribs and furrows, and a spiny margin. The pygidia of Emuella and Balcoracania however are poorly differentiated, minute, and have a smooth margin. Later scholars therefore placed Holyoakia in the Dorypygidae. Distribution Balcoracania dailyi occurs in the late Lower Cambrian (late Botomian) of South Australia (White Point conglomerate, Cape d' Estaing and Emu Bay sections, Kangaroo Island; Warragee Member, Billy Creek Formation, Flinders Range; Coads Hill Member, Billy Creek Formation, Reaphook Hill). Balcoracania sp. has been collected from the Lower Cambrian of Antarctica (Shackleton Limestone, central Transantarctic Mountains). Emuella dalgarnoi is found in the late Lower Cambrian (late Botomian) of South Australia (Emu Bay Shale, Kangaroo Island). Emuella polymera has been collected from the late Lower Cambrian (late Botomian) of South Australia (Cape d' Estaing section, Kangaroo Island). Key to the species References External links photographs of Balcoracania dailyi photographs and line-drawing of Emuella polymera Cambrian trilobites Emuelloidea Trilobite families