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Nasocephalus

Trilobita - Ptychopariida - Marjumiidae

Taxonomy
Nasocephalus was named by Wilson (1954) [Sepkoski's age data: Cm uMid Cm Dres-l Sepkoski's reference number: 80]. Its type is Nasocephalus nasutus.

It was assigned to Crepicephalidae by Wilson (1954); to Marjumiidae by Jell and Adrain (2002); and to Ptychopariida by Sepkoski (2002).

Species
N. nasutus (type species)

Synonymy list
YearName and author
1954Nasocephalus Wilson p. 268
2002Nasocephalus Jell and Adrain p. 409
2002Nasocephalus Sepkoski

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Ecdysozoa
Panarthropoda
phylumArthropodaLatreille 1829
RankNameAuthor
subphylumArtiopoda(Hou and Bergstrom)
classTrilobitaWalch 1771
subclassLibristoma
orderPtychopariidaSwinnerton 1915
familyMarjumiidaeKobayashi 1935
genusNasocephalus

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

G. †Nasocephalus Wilson 1954
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Nasocephalus nasutus Wilson 1954
Diagnosis
ReferenceDiagnosis
J.L. Wilson 1954Cranidium of moderate size (less than 1 cm. long), longer than wide, moderate relief to individual parts. Glabella prominent but not highly arched, rather depressed posteriorly but well defined by dorsal furrow which shallows anteriorlv,., well taoered and rounded anteriorly, with occipital ring occupying about two-thirds of axial length disregarding anterior spine; three pairs of very faint glabellar furrows, posterior two curved sharply backwards proximally; occipital ring projected backward axially, occipital spine may be present. Frontal area highly variable, brim very short but border projected anteriorly a t axis. Fixed cheeks narrow (one-fourth to one-third basal glabellar width), elevated and convex, bearing wellmarked obliquely backward trending ocular ridges and small semicircular palDebral lobes elevated above them and locatedAabout on the midwidth line through glabella; posterior limbs narrow and extended straight out, deeply furrowed.

Facial suture cuts anterior margin a t long axis on non-spinose species, proceeds straight back to eye from anterolateral corners of cranidium, indents slightly behind same and trends straight out along posterior limbs.

A pygidium assigned questionably to one of the species of this genus is figured. It is convex, a little wider than long, with a large elevated axis bearing three segments and a terminal portion; pleural lobes well marked by two or three interpleural grooves which fade out posterolaterally; border lacking.
Measurements
No measurements are available
Composition: low Mg calcitec
Composition 2: chitinc
Ontogeny: molting, addition of partsc
Environment: marinec
Locomotion: fast-movingc
Life habit: low-level epifaunalc
Diet: carnivorec
Vision: well-developedf
Created: 2009-12-19 04:23:22
Modified: 2009-12-19 06:23:22
Source: f = family, c = class
References: Aberhan et al. 2004, Whittington et al. 1997

Age range: base of the Marjumian to the top of the Dresbachian or 504.50000 to 485.40000 Ma

Collections (7 total)


Time interval Ma Country or state Original ID and collection number
Marjumian504.5 - 497.0USA (Texas) N. flabellatus (228 78733) N. nasutus (78734 78735)
Dresbachian497.0 - 485.4Canada (Yukon) N. flabellatus (55216 55217 55220)