''Emuella'' is a genus of

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

s of the family

Emuellidae Emuellidae are a small family of trilobites, a group of extinct marine arthropods, that lived during the late Lower Cambrian (late Botomian) of the East Gondwana supercontinent, in what are today South-Australia and Antarctica. Description E ...

. Its fossils have been found in

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

Etymology

The genus name means "little emu", and refers to Emu Bay, on

Kangaroo Island Kangaroo Island (, ) is Australia's third-largest island, after Tasmania and Melville Island, Northern Territory, Melville Island. It lies in the state of South Australia, southwest of Adelaide. Its closest point to the mainland is Snapper Poi ...

, one of the sites where fossils of ''Emuella'' have been collected. The species

epithet An epithet (, ), also a byname, is a descriptive term (word or phrase) commonly accompanying or occurring in place of the name of a real or fictitious person, place, or thing. It is usually literally descriptive, as in Alfred the Great, Suleima ...

''polymera'' is derived from Greek words πολύ -poly- meaning "many"; and μέρος -meros- meaning "part", for the many segmented thorax. ''E. dalgarnoi'' is named after R.C. Dalgarno, who discovered ''Balcoracania dailyi'' in the

Flinders Ranges The Flinders Ranges are the largest mountain ranges in South Australia, which starts about north of Adelaide. The ranges stretch for over from Port Pirie to Lake Callabonna. The Adnyamathanha people are the Aboriginal group who have inhab ...

, near

Blinman Blinman is a locality incorporating two towns in the Australian state of South Australia within the Flinders Ranges about north of the state capital of Adelaide city centre, Adelaide. It includes the highest surveyed town in South Australia, wi ...

, South Australia.

Description

It can be recognised by touching glabella and frontal border, and the sub-pentagonal head, as compared to, a short field between the front of the axis in the head or glabella and the border ridge, and a semi-circular headsheald in the sister-genus '' Balcoracania''. Both emuellid genera share eye ridges that are positioned parallel to the frontal and lateral border of the head, prominent genal spines that are a smooth continuation of the lateral margin of the head, a prothorax of 6 segments, with the 5th and 6th merged and carrying large trailing spines. Both genera have in adulthood a highly variable but large number of segments of the opistothorax, although the largest number found in ''B. dailyi'' with 97 is much larger than in ''Emuella'' (52).

References

Further information

* * * * * Cambrian trilobites Emuelloidea Trilobites of Oceania Redlichiida genera Fossil taxa described in 1970 Emu Bay Shale Cambrian genus extinctions {{redlichiida-stub