Nevadia

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Nevadia
Temporal range: Atdabanian 524–521  Ma
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NevadiaSp.jpg
Nevadia sp.
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Class:† Trilobita
Order:† Redlichiida
Suborder:† Olenellina
Superfamily:† Nevadioidea
Family:† Nevadiidae
Genus:† Nevadia
Walcott, 1910
Species
  • N. weeksiWalcott, 1910 (Type)
  • N. addyensisOkulitch, 1951
  • N. faceta(Fritz, 1972)
  • N. fritziLieberman, 2001
  • N. gracile(Walcott, 1910)
  • N. ovalisMcMenamin, 1987
  • N. parvoconicaFritz, 1992
  • N. saupeaeGapp, 2011

Nevadia is an extinct genus of trilobites, fossil marine arthropods, with species of average size (about 3.5 centimetres or 1.4 inches long). It lived during the Atdabanian stage, which lasted from 530 to 524 million years ago, in what are today Western Canada, the Western United States, and Mexico.

Contents

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 who worked on olenelloid trilobites.

Description

The body of Nevadia is very flat dorso-ventrally. The general outline of its thin, lightly calcified exoskeleton is inverted wide drop-shaped. The front is rounded, widest at the back of the headshield (or cephalon), and tapering from there to an eventually rounded termination. The central area of the cephalon (or glabella) 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 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) is very small and subquadrate in shape. [1]

Distribution

Nevadia weeksi from the Poleta Formation Nevadia weeksi CRF.jpg
Nevadia weeksi from the Poleta Formation

Taxonomic

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

Species previously assigned to Nevadia

Habitat

Nevadia species were probably marine bottom dwellers, like all Olenellina.

Related Research Articles

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Olenellus is an extinct genus of redlichiid trilobites, with species of average size. It lived during the Botomian and Toyonian stages (Olenellus-zone), 522 to 510 million years ago, in what is currently North-America, part of the palaeocontinent Laurentia.

Emuellidae Extinct family of trilobites

Emuellidae are a small family of trilobites, a group of extinct marine arthropods, that lived during the late Lower Cambrian of the East Gondwana supercontinent, in what are today South-Australia and Antarctica. Emuellidae can be recognized among trilobites in having a set of unique features. The headshield or cephalon has large genal spines reaching back as far as the 3rd to 6th segment of the thorax. The eye-ridges contact the back of the frontal lobe of the glabella and extend laterally and backwards, roughly parallel to the frontal and lateral rim of the cephalon. There are small, clearly incised pits at the junction between the eye-ridge and the frontal lobe of the cephalic axis. The thorax reaches its greatest width at the 6th segment. The frontal part or prothorax consists of 6 segments, with number 5 and 6 fused, and the 6th carrying very large trailing spines. The rear part or opistothorax consists of a variable but extremely large number of segments.

<i>Acontheus</i> Extinct genus of trilobites

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Laudonia is an extinct genus of trilobites that lived during the early part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. There are currently two named species assigned to it.

<i>Wanneria</i>

Wanneria is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the later part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. Wanneria walcottana is the only known species in this genus.

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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.

<i>Nevadella</i>

Nevadella is an extinct genus of trilobites, fossil marine arthropods, with species of average size. It lived during the late Atdabanian stage, which lasted from 530 to 524 million years ago during the early part of the Cambrian Period.

<i>Nephrolenellus</i>

Nephrolenellus is an extinct genus of trilobite, fossil marine arthropods, of relatively small size. Currently two species are attributed to it. Nephrolenellus lived at the end of the Lower Cambrian. Species are known from the Great Basin of California, Nevada and Arizona, with one specimen from Canada.

<i>Pagetia</i>

Pagetia Walcott, 1916. is a small genus of trilobite, assigned to the Eodiscinid family Pagetiidae and which had global distribution during the Middle Cambrian. The genus contains 55 currently recognized species, each with limited spatial and temporal ranges.

Holmiidae

Holmiidae is a family of trilobites, that lived during the Lower Cambrian (Atdabanian). The Holmiidae is a diverse family of eight genera containing at least 17 species. It includes some of the earliest trilobites of Baltica. Holmiidae occur throughout Baltica and Western Laurentia, and also in Morocco.

Acmarhachis is a genus of trilobite in the order Agnostida, which lived in what are now Australia, Canada, China (Anhui), Kazakhstan, Russia (Kharaulakh), and the US. It was described by Resser in 1938, and the type species is Acmarhachis typicalis.

<i>Bristoliinae</i>

The Bristoliinae is an extinct subfamily of trilobites, fossil marine arthropods, with species of small to average size. Species belonging to this subfamily lived during the Botomian and Toyonian stage (Olenellus-zone), 522-513 million years ago, in the former continent of Laurentia, including what are today Mexico, the Appalachian Mountains and the south-western United States, and Canada.

Lochmanolenellus is an extinct genus of trilobites, fossil marine arthropods, with one small species, L. mexicana. It lived during the Botomian stage (Olenellus-zone), 522–513 million years ago, in the South-West of the former continent of Laurentia, in what are today Mexico, and the South-Western United States.

Bolbolenellus is an extinct genus of trilobites, fossil marine arthropods, with five species attributed to it currently. It can be easily distinguished from all other trilobites by the combination of the absence of dorsal sutures in the head shield like all Olenellina, and a distinctly bulbous frontal lobe (L4) of the raised axial area in the head called glabella. The species lived at the end of the Lower Cambrian.

<i>Mallagnostus</i>

Mallagnostus Howell, 1935, is a trilobite genus belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida Salter (1864) according to Whittington et al. 1997. It lived during the late Lower Cambrian, with remains found in USA, Canada (Newfoundland), Spain, England, Russia, Mongolia, and the early Middle Cambrian as reported from China and Russia (Yakutia).

<i>Thoracocare</i>

Thoracocare is a minute to very small trilobite, that lived during part of the Middle Cambrian in what are today the states of Idaho, Nevada and Utah. It is the only trilobite known with just two thorax segments outside most members of the Agnostida order. It can be distinguished from Agnostida by the very wide subquadrate glabella, parallel-side or widening forward in the largest specimen, with the full front side touching the border. Two species are known, one, T. idahoensis, only from pygidia.

<i>Cedaria</i>

Cedaria is a small, rather flat trilobite with an oval outline, a headshield and tailshield of approximately the same size, 7 articulating segments in the middle part of the body and spines at the back edges of the headshield that reach halflength of the body. Cedaria lived during the early part of the Upper Cambrian (Dresbachian), and is especially abundant in the Weeks Formation.

<i>Orygmaspis</i>

Orygmaspis is a genus of asaphid trilobite with an inverted egg-shaped outline, a wide headshield, small eyes, long genal spines, 12 spined thorax segments and a small, short tailshield, with four pairs of spines. It lived during the Upper Cambrian in what are today Canada and the United States.

William Harold Fritz was a geologist who worked for the Geological Survey of Canada. He is known for his work in stratigraphy and on olenelloid trilobites.

References

  1. ↑ H. B. Whittington; et al. (1997). "Introduction, Order Agnostida, Order Redlichiida". Treatise on Invertebrate Paleontology. Part O, Revised. Trilobita.
  2. 1 2 Gapp, I. Wesley; Lieberman, Bruce S.; Pope, Michael C.; Dilliard, Kelly A. (2011). "New olenelline trilobites from the Northwest Territories, Canada, and the phylogenetic placement of Judomia absita Fritz, 1973" (PDF). Zootaxa. 2918 (2918): 15–28. doi:10.11646/zootaxa.2918.1.2. ISSN   1175-5334 . Retrieved 21 November 2012.
  3. 1 2 W. H. Fritz. 1992. "Walcott's Lower Cambrian Olenellid trilobite collection 61k, Mount Robson Area, Canadian Rocky Mountains". Geological Survey of Canada Bulletin 432. 1–66
  4. 1 2 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 42–46.
  5. ↑ W. H. Fritz (1995). "Esmeraldina rowei and associated Lower Cambrian trilobites (1f fauna) at the base of Walcott's Waucoban Series, southern Great Basin, U.S.A." Journal of Paleontology69 (4): 708–723
  6. ↑ J. Stewart, M. A. S. McMenamin, and J. M. Morales-Ramirez (1984). "Upper Proterozoic and Cambrian rocks in the Caborca Region, Sonora, Mexico - physical stratigraphy, biostratigraphy, paleocurrent studies, and regional relations". U. S. Geological Survey Professional Papers (1309)1–33.
  7. ↑ J.J. Sepkoski Jr. 1998
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