''Nevadia'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of redlichiid

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, with species of average size (about long). It lived during the

Atdabanian Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approxi ...

stage, which lasted from 530 to 524 million years ago, in what are today Western Canada, the Western United States, and Mexico.

Etymology

''Nevadia'' is named for the US State of Nevada, where the first specimens of this genus where found. ''N. fritzi'' in named in honor of W.H. Fritz, a

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

who worked on olenelloid trilobites.

Description

The body of ''Nevadia'' is very flat dorso-ventrally. The general outline of its thin, lightly calcified

exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...

is inverted wide drop-shaped. The front is rounded, widest at the back of the headshield (or

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino Jr., Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont ...

), and tapering from there to an eventually rounded termination. The central area of the cephalon (or

glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior ...

) is distinctly tapered forward, sides slightly concave, but not wedging out in the frontal half and with a narrow rounded front. The glabella and the frontal margin do not touch (in jargon: the preglabellar field is present). Cephalic margin clearly less wide as the most frontal thoracal segment. The

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

has 27 segments. The segments look a bit degenerated behind the 15th to 18th (or an opisthothorax can be distinguished). The pleural spines are long and sickle-shaped. The tailshield (or

pygidium The pygidium (: pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compos ...

) is very small and subquadrate in shape.

Distribution

*''Nevadia ovalis'' occurs in the Lower Cambrian of the Northwest Territories, Canada (Sekwi Formation, Mackenzie Mountains), and Mexico (Senora). *''Nevadia parvoconica'' and ''Nevadia sp.'', have been collected at the Mural Formation, Mumm Peak Section, Canada, .W. H. Fritz. 1992. "Walcott's Lower Cambrian Olenellid trilobite collection 61k, Mount Robson Area, Canadian Rocky Mountains". ''Geological Survey of Canada Bulletin'' 432. 1–6

/ref> *''Nevadia weeksi'' and ''Nevadia sp.'', were found at Cinnamon Peak-Whitehorn Mountain, Section, Mural Formation, Canada, ; and at the Montenegro Member, Campito Formation, Esmeralda County, Nevada, USA.J. S. Hollingsworth (1999). "A second candidate position for the base of the Montezuman". ''Laurentai'' 99: V field conference of the Cambrian Stage Subdivision Working Group, International Subcommission on Cambrian Stratigraphy 42–4

http://paleodb.geology.wisc.edu/cgi-bin/bridge.pl?action=basicCollectionSearch&collection_no=10496] *''Nevadia weeksi'' occurs near the base of the Montenegro Member, Campeto Formation, Northeast of Barrel Spring, Nevada, USA, . *''Nevadia sp.'', was collected at Puerto Blanco, Unit 3, Cerro Rajon, Caborca Region, Mexico, ; and at the ''Nevadella'' zone, Old Dominion Limestone Formation, Colville, Washington, USA, .J.J. Sepkoski Jr. 1998
/ref> *''Nevadia parvoconica'', was found at the Middle Member of the Poleta Formation, Esmeralda County, Nevada, USA. *''Nevadia saupeae'', was recovered from the Sekwi Formation, Mackenzie Mountains, Northwest Territories, Canada

Taxonomic

''Nevadia'' predates ''Nevadella'' and according to cladistic analysis includes its direct ancestor.

Species previously assigned to Nevadia

* ''Nevadia crosbyi'' = '' Callavia broegeri''

Habitat

''Nevadia'' species were probably marine bottom dwellers, like all

Olenellina Olenellina is a suborder of the order Redlichiida of trilobites that occurs about halfway during the Lower Cambrian, at the start of the stage called the Atdabanian. Olenellina are arguably the earliest trilobites in the fossil record as members ...

References

{{Taxonbar, from=Q1217366 Redlichioidea Redlichiida genera Cambrian trilobites Cambrian trilobites of North America Paleontology in Washington (state) Paleozoic life of Alberta Paleozoic life of British Columbia