''Nevadella'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

trilobites Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

marine

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

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

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 approxim ...

stage, which lasted from 530 to 524 million years ago during the early part of the

Cambrian Period The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

Etymology

The name is derived from ''

Nevadia ''Nevadia'' is an extinct genus of trilobites, fossil marine arthropods, with species of average size (about long). It lived during the Atdabanian stage, which lasted from 530 to 524 million years ago, in what are today Western Canada, the West ...

'', a related genus.

Taxonomy

''Nevadia'' predates ''Nevadella'' and may include its direct ancestor.

Species previously assigned to ''Nevadella''

* ''N. burri'' = ''Pleisionevadella burri''

Description

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

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

is inverted 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., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont Company. Baldino s ...

), 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 to ...

) is distinctly tapered forward, sides slightly concave, but wedging out slightly in the frontal half and with a rounded front (like the silhouette of a slim pawn). The glabella and the frontal margin almost or entirely touch (in jargon: the preglabellar field is short or absent). Cephalic margin at least as wide as the most frontal thoracal segment. The

thorax The thorax or chest is a part of the anatomy of humans, 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 divisions of the cre ...

has 17 to 23 segments, gradually diminishing in size. The pleural spines are long and sickle-shaped. The tailshield (or

pygidium The pygidium (plural 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 compo ...

) is very small and subquadrate in shape.

Distribution

Fossils of ''Nevadella'' have been found in the late Atdabanian of the USA (California, Nevada) and Canada (Cordilleran region). * ''N. eucharis'' is known from the Middle Member of the Poleta Formation, Esmeralda County, Nevada, USA. * ''N. keelensis'' is known from the Sekwi Formation, Northwest Territories, Canada. * ''N. mountjoyi'' is known from the Mural Formation, north slope of Mount Mumm, Alberta, Canada. * ''N. perfecta'' is known from the Mahto Formation, Mumm Peak on the west side of Hitka Pass, western Alberta, Canada.U. S. National Museum, Catalogue No. 60082.

Ecology

Contemporary

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

that also occur in the so-called "Nevadella" Zone include ''Esmeraldina'', ''Holmiella'', ''Palmettaspis'', ''

Bradyfallotaspis ''Bradyfallotaspis'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the late Atdabanian stage, during the early part of the Cambrian Period The Cambrian Period ( ; sometimes symbolize ...

'', ''

Geraldinella ''Geraldinella'' 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 T ...

'', ''

Paranevadella ''Paranevadella'' 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 ...

'', ''

Buenellus ''Buenellus higginsi'' is an average size (about ) trilobite, which lived during the Lower Cambrian period, in what is now North-West Greenland. It is a prominent member of the Sirius Passet fauna. ''Buenellus higginsi'' is the only known specie ...

'', and ''

Cirquella ''Cirquella'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Atdabanian stage, in the former continent Laurentia. Description Only the thin and lightly calcified headshields (or cep ...

''.

Habitat

''Nevadella'' species were probably marine bottom dwellers, like all Olenellina.

References

{{Taxonbar, from=Q7003688 Redlichioidea Cambrian trilobites of North America Paleozoic life of Alberta Paleozoic life of British Columbia Cambrian genus extinctions