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Trilobita - Agnostida - Marjumiidae

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 Ptychopariida by Sepkoski (2002); and to Marjumiidae by Jell and Adrain (2003).

Synonymy list
YearName and author
1954Nasocephalus Wilson p. 268
2002Nasocephalus Sepkoski, Jr.
2003Nasocephalus Jell and Adrain p. 409

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EubilateriaAx 1987
phylumArthropodaLatreille 1829
classTrilobitaWalch 1771
orderAgnostidaSalter 1864
superfamilyAgnostoideaM'Coy 1849
familyMarjumiidaeKobayashi 1935

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.

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.