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Olenellus (Mesolenellus)

Trilobita - Redlichiida - Olenellidae

Taxonomy
Olenellus (Mesolenellus) was named by Palmer and Repina (1993) [Sepkoski's age data: Cm Atda-u Cm Boto-u]. Its type is Holmia hyperborea.

It was reranked as Mesolenellus by Lieberman (1998), Lieberman (1999) and Sepkoski (2002).

It was assigned to Olenellus by Palmer and Repina (1993); to Olenellinae by Lieberman (1998); to Mesonacinae by Lieberman (1999); and to Olenellida by Sepkoski (2002).

Synonymy list
YearName and author
1993Olenellus (Mesolenellus) Palmer and Repina p. 22
1998Mesolenellus Lieberman p. 70
1999Mesolenellus Lieberman p. 34
2002Mesolenellus Sepkoski

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Ecdysozoa
Panarthropoda
phylumArthropodaLatreille 1829
Life
subphylumArtiopoda(Hou and Bergstrom)
RankNameAuthor
classTrilobitaWalch 1771
orderRedlichiidaRichter 1932
suborderOlenellina
superfamilyOlenelloidea
familyOlenellidae
subfamilyOlenellinae
genusOlenellusHall 1861
subgenusMesolenellus

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.

Subg. †Olenellus (Mesolenellus) Palmer and Repina 1993
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Diagnosis
ReferenceDiagnosis
A. R. Palmer and L. N. Repina 1993Species of Olenellus with posterior margin of cephalon directed slightly forward distal to position of intergenal spine or intergenal angle. Sagittal length of preglabellar field equal to or slightly greater than sagittal length of border. Intergenal spine or angle about midway between genal spine and axial furrow or closer to axial furrow. Posterior tips of ocular lobes convergent towards glabella, situated opposite or posterior to occipital furrow.
B. S. Lieberman 1999Anterior cephalic border anterolateral of frontal lobe length (exsag.) 0.75 times length (exsag.) of L2 at distal tip; anterior cephalic border elevates from anterior border furrow at approximately 45 degree angle relative to dorsal flat plane, then intersects raised lineament, anterior of this point, border lies in flattened dorsal plane before deflecting ventrally; anterior part of frontal lobe does not intersect anterior border furrow; lateral margins of frontal lobe deflected as far laterally as lateral margins of L0; distal margins of glabella opposite L2 subparallel; S2 straight, not conjoined medially; lateral margins of glabella between posterior margin of L0 and point midway forward on distal tip of L1 subparallel; line from posterior tip of ocular lobe to junction of ocular lobes with glabella forms roughly 5 degree angle with sagittal line; S0 conjoined medially; lateral lobes pre- sent on L0; posterior margin of ocular lobes opposite medial part of distal margin of L0; glabellar furrows faintly incised; intergenal angle forms 30 to 35 degree angle with trans- verse line; genal spine length (exsag.) approximately length (sag.) of 8 to 10 thoracic seg- ments; pleural spine of T3 extends back 6 to 8 thoracic segments; anterior margin of T3 roughly parallels a transverse line medially; posterior margin of pleural furrow of T3 par- allels transverse line before flexing posterolaterally; thoracic pleural spines behind T3 ex- tend back 4 to 7 segments posteriorly; spines wide (tr.), one-half length (exsag.) of corre- sponding pleural segment at its medial part; width (tr.) of thoracic axis 100% of width of pleural field excluding spines; base of large axial spine on T15 less than half width (tr.) of axis of segment.