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Mesonacis vermontanus

Trilobita - Redlichiida - Olenellidae

Taxonomy
Olenus vermontana was named by Hall (1859) [Original holotype, ANMH 230, reported lost by Shaw 1955. Neotype designated by Lieberman 1999. [not] Olenellus vermontanus KINDLE & TASCH, 1948, Canadian Field-Naturalist, vol. 62, p. 136, pl. 1, figs. 5, 6= O. brachycephalus.]. Its type specimen is USNM 15399a, a cephalon/head, and it is a 3D body fossil. It is the type species of Mesonacis.

It was recombined as Paradoxides vermontana by Emmons (1860), Billings (1861), Barrande (1861) and Billings (1862); it was recombined as Barrandia vermontana by Hall (1860), Hall (1861) and Hall (1862); it was recombined as Olenellus vermontana by Billings (1865) and Holm (1887); it was recombined as Olenellus vermontanus by Ford (1881), Resser and Howell (1938) and Shaw (1955); it was recombined as Mesonacis vermontana by Walcott (1885), Walcott (1886), Moberg (1899) and Walcott (1910); it was recombined as Elliptocephalus (Schmidtia) vermontana by Marcou (1890); it was recombined as Olenellus (Mesonacis) vermontana by Walcott (1891) and Cole (1892); it was recombined as Olenellus (Mesonacis) vermontanus by Palmer and Repina (1993); it was recombined as Mesonacis vermontanus by Lieberman (1999).

Synonymy list
YearName and author
1859Olenus vermontana Hall pp. 60- 61 fig. 2
1860Paradoxides vermontana Emmons p. 280
1860Barrandia vermontana Hall p. 117
1861Paradoxides vermontana Barrande pp. 277-278 figs. Pl. 5, Fig. 8
1861Paradoxides vermontana Billings p. 11
1861Barrandia vermontana Hall p. 370
1862Paradoxides vermontana Billings pp. 101-104
1862Barrandia vermontana Hall p. 370 figs. pl. 13 f. 2, not 4-5
1865Olenellus vermontana Billings p. 11
1881Olenellus vermontanus Ford p. 258
1885Mesonacis vermontana Walcott p. 330 figs. 1, 2
1886Mesonacis vermontana Walcott pp. 158-162 figs. Pl. 24, Figs I, Ia-b
1887Olenellus vermontana Holm pp. 515-516
1890Elliptocephalus (Schmidtia) vermontana Marcou p. 363
1891Olenellus (Mesonacis) vermontana Walcott p. 637 figs. Pl. 87, FIgs I, Ia-b
1892Olenellus (Mesonacis) vermontana Cole pp. 340-341 figs. Fig. 2
1899Mesonacis vermontana Moberg p. 318 figs. Pl. 14, Fig. 4
1910Mesonacis vermontana Walcott p. 264 figs. Plate 26, Figs. 1-3
1938Olenellus vermontanus Resser and Howell p. 220
1955Olenellus vermontanus Shaw pp. 793 - 794 figs. pl. 75 f. 10
1993Olenellus (Mesonacis) vermontanus Palmer and Repina p. 22
1999Mesonacis vermontanus Lieberman p. 41

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RankNameAuthor
kingdomAnimalia()
—Bilateria
—EubilateriaAx 1987
—Protostomia
—Ecdysozoa
—Panarthropoda
phylumArthropodaLatreille 1829
subphylumArtiopoda(Hou and Bergstrom)
RankNameAuthor
classTrilobitaWalch 1771
orderRedlichiidaRichter 1932
suborderOlenellina
superfamilyOlenelloidea
familyOlenellidae
subfamilyMesonacinae(Walcott 1891)
genusMesonacis
speciesvermontanus()

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.

†Mesonacis vermontanus Hall 1859
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Diagnosis
ReferenceDiagnosis
A. B. Shaw 1955Olenellus with ten thoracic segments and a pygidium behind the spined fifteenth segment. The eyes are short with the posterior extremities lying opposite the pre-occipital lobe of the glabella, unlike O. thompsoni. Glabella long, with second pair of furrows behind anterior lobe short and incomplete.