Olenellina

Olenellina
Mesonacis vermontanus , a trilobite of the suborder Olenellina © Sam Gon III
Conservation status
Fossil
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Trilobita
Order:	Redlichiida
Suborder:	Olenellina
Superfamilies
Superfamily Olenelloidea Olenellidae Mesonacis vermontanus (Hall, 1859) Mesonacis bonnensis (Resser and Howell) Mesonacis bristolensis Resser, 1928 Mesonacis fremonti (Walcott, 1910) Mesonacis insolence Resser Mesonacis eagerensis Holmiidae Superfamily Fallotaspidoidea Archaeaspididae Fallotaspididae Judomiidae Neltneriidae Nevadiidae Nevadia

Olenellina is a suborder of the order Redlichiida of Trilobites. The suborder contains two superfamilies: Olenelloidea (with 2 families), and Fallotaspidoidea (with 5 families). The Olenillina are some of the most primitive trilobites. They originated at the beginning of the Cambrian era and became extinct at the end of the lower Cambrian.

Physiology

(See Trilobite: Terminology for definitions of morphological terms)

Cephalon: Lacking facial sutures and the glabella typically has rather deep lateral furrows. In some species the front glabellar lobe is an almost circular boss. There is a conterminant hypostome with a very wide rostral plate extending between genal angles, with a perrostral suture (no connective sutures).

Thorax: Numerous segments, is non-fulcrate with the axis often spine-bearing.

Pygidium: Narrow, with few segments.

Olenellina are the earliest trilobites in Cambrian stratigraphy. No calcified protaspis is known, the body is flattened and the cuticle is thin.

References

• Hagadorn, J.W. (2002). "Burgess Shale-type Localities: The global picture". In 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". http://www.austmus.gov.au/palaeontology/research/trilobites03.htm?. Retrieved August 23, 2005. 
• Sam Gon III. "A guide to the Orders of Trilobites". http://www.trilobites.info/index.htm. Retrieved 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". http://info.esc.net.au/~dasimpson/index.htm. Retrieved August 23, 2005.