[1] (See the Trilobite article for a definition of morphological terms) Cephalon: Cranidium subquadrate, glabella cylindrical, slightly contracted at S3, three pairs of glabellar furrows, preglabellar field short or absent, eye ridge wide, long, directed slightly postero-laterally, palpebral lobe cresentic, posterior area of fixigena with fulcrum, free cheeks (or librigenae) with long spines; hypostome conterminant, attached to a narrow rostral plate.

The primitive features prompted the theory that the Emuellids actually represented the stem group of all trilobites, with the Olenellina having secondary fused facial sutures.

[4] Most recently, the Emuellidae are regarded an early branch of the Redlichiina suborder, the closest relatives being the genera Bigotina, Abadiella, and the close-knit group of the families Estaingiidae, Ichangiidae and Ellipsocephalidae.

[5] 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.

[1] 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;[6] Warragee Member, Billy Creek Formation, Flinders Range;[6][7] Coads Hill Member, Billy Creek Formation, Reaphook Hill).