Emuellidae
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 Balcoracania dailyi of the Emuellidae family
Lower Cambrian Emu Shale Kangaroo Island, South Australia © Dave Simpson |
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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.
[edit] 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.
[edit] References
- Hagadorn, J.W. (2002). “Burgess Shale-type Localities: The global picture”, Bottjer, D.J., W. Etter, J.W. Hagadorn & C.M. Tang, eds: Exceptional Fossil Preservation -- A Unique View on the Evolution of Marine Life. Columbia University Press. ISBN 0231102542.
- Greg Edgecombe and the Australian Museum. Australian Trilobites: A Species List and Bibliography. Retrieved on August 23, 2005.
- Sam Gon III. A guide to the Orders of Trilobites. Retrieved on August 23, 2005.
- Nedin, C. (1995). "The Emu Bay Shale, a Lower Cambrian fossil Lagerstätte, Kangaroo Island, South Australia". Memoirs of the Association of Australasian Palaeontologists 18: 31-40.
- Simpson, Dave. Trilobites of South Australia. Retrieved on August 23, 2005.
