Emuellidae

Taxobox
name = "Emuellidae"


image_width = 240px
image_caption = "Balcoracania dailyi" of the Emuellidae family
Lower Cambrian Emu Shale
Kangaroo Island, South Australia
© Dave Simpson
regnum = Animalia
phylum = Arthropoda
classis = Trilobita
ordo = Redlichiida
subordo = Redlichiina
superfamilia = Emuelloidea
familia = Emuellidae
familia_authority = Pocock, 1970
subdivision_ranks = Genera
subdivision =
* "Emuella"
* "Balcoracania"
* "Holyoakia"

Emuellidae is the only family of trilobites of the super-family Emuelloidea. Their fossils are found chiefly in Australia, and in fact draw their name from the Emu Bay shales, in Southern Australia, the Lagerstätte at which they were first found. They were first described by Dr. B Daily, of the Geology Department, University of Adelaide in 1956. The family contains three genera: Emuella, Balcoracania, and Holyoakia.

Physiology

(See the Trilobite article for a definition of morphological terms)

Cephalon: Cranidium subquadrate, glabella cylindrical, slightly contracted at S3, 3 pairs of glabellar furrows, preglabellar field short or absent, eye ridge wide, long, directed slightly posterolaterally, palpebral lobe cresentic, posterior area of fixigena with fulcrum, librigena with long genal spine; hypostome conterminant, attached to narrow rostral plate.

Thorax: Divided into prothorax of 6 segments (6th macropleural) and extremely long opisthothorax of 42-55 segments (an emuellid holds the record for greatest number of thoracic segments in a trilobite species).

Pygidium: A minute, segmented disc.

References