Emuellidae
Encyclopedia
Emuellidae is the only family of trilobite
s 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
.
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.
Trilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
s 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
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
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
Emuella
Emuella is a genus of trilobites of the family Emuellidae. Their fossils are found chiefly in Lower Cambrian strata of Australia....
, Balcoracania
Balcoracania
Balcoracania is a genus of trilobite of the family Emuellidae. Their fossils are found chiefly in Australia....
, and Holyoakia
Holyoakia
Holyoakia is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the late Atdabanian stage, which lasted from 530 to 524 million years ago during the early part of the Cambrian Period. It usually is found near the fossilized remains of pods of...
.
Physiology
(See the TrilobiteTrilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
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
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
: 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
Pygidium
The pygidium is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. It contains the anus and, in females, the ovipositor...
: A minute, segmented disc.