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Elliptocephala

Trilobita - Redlichiida - Holmiidae

Taxonomy
Elliptocephala was named by Emmons (1844) [Sepkoski's age data: Cm Boto-u].

It was synonymized subjectively with Olenus by Hall (1847); it was reranked as Olenellus (Elliptocephalus) by Ford (1877); it was replaced with Georgiellus by Moberg (1899); it was corrected as Elliptocephalus by Whittington et al. (1997) and Sepkoski (2002).

It was assigned to Olenellus by Ford (1877); to Mesonacidae by Walcott (1910); to Holmiinae by Palmer and Repina (1993); to Wanneriidae by Lieberman (1999); to Olenellida by Sepkoski (2002); and to Holmiidae by Whittington et al. (1997) and Jell and Adrain (2003).

Synonymy list
YearName and author
1844Elliptocephala Emmons p. 21
1877Olenellus (Elliptocephalus) Ford pp. 265-272 figs. Pl. 4, Figs 1 - 10
1910Elliptocephala Walcott p. 267
1993Elliptocephala Palmer and Repina p. 26 fig. 6.7
1997Elliptocephalus Whittington et al. p. 414
1999Elliptocephala Lieberman p. 53
2002Elliptocephalus Sepkoski, Jr.
2003Elliptocephala Jell and Adrain p. 370

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Ecdysozoa
Panarthropoda
phylumArthropodaLatreille 1829
RankNameAuthor
subphylumMandibulata
classTrilobitaWalch 1771
orderRedlichiidaRichter 1932
suborderOlenellina
familyHolmiidaeHupé 1953
genusElliptocephala

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.

Diagnosis
ReferenceDiagnosis
A. R. Palmer and L. N. Repina 1993Holmiinae with posterior margin of cephalon straight or slightly angled forward distal to intergenal swelling. Intergenal spine absent. Posterior tips of ocular lobes opposite or slightly anterior to occipital furrow. Sagittal length of preglabellar field equal to or slightly greater than that of anterior border. Thorax mod- erately wide, consisting of 18 segments, pleural regions of adults lacking macropleurae. Fifteenth through eighteenth segments with strong axial spines. Pygidium small, subquadrate, with single pair of short an terolateral spines. External surface with some reticulate areas.
B. S. Lieberman 1999Length (sag.) of L4 equal to roughly 1.5 times length of L0 and L1 (sag.); anterior margins of frontal lobe at each side of midline deflected posteriorly at roughly 40 de- gree angle relative to transverse line; lateral margins of L4 distal to lateral margins of L0; preocular furrow on L4 directed inward and forward from glabellar margin; posterior margins of L4 divergent anteriorly; distal margins of L3 convex outward; middle sector of S3 convex anteriorly; L2 and L3 do not merge; distal margins of L2 diverging anteriorly; line between ends of S2 transverse; S2 convex anteriorly; ocular lobe with prominent ocu- lar furrow; line from posterior tip of ocular lobe to junction of posterior margin of lobe with glabella forms 10 to 20 degree angle with sagittal line; anterodistal margins of L3 formed by ocular lobes; intergenal angle developed posterior of point halfway between oc- ular lobes and genal spine angle; genal and intergenal ridges prominently developed; dis- tal sector of S0 with proximal end well posterior of distal end; axial part of L0 with node; posterior margin of L0 convex posteriorly; lateral lobes on L0 absent; thoracic pleural fur- rows extend onto spines; length (exsag.) of furrows equal to length of posterior band; an- terior margin of thoracic pleural furrow on T3 parallels a transverse line before flexing strongly posteriorly; long spine on 15th thoracic segment, spine broad (tr.) at its base; py- gidium twice as broad as long, posterior margin weakly convex.