Redlichiida

Mesonacis eagerensis

Order Redlichiida / Suborder Olenellina / Superfamily Olenelloidea / Family Olenellidae

Cambrian, Series 2, Stage 4Canada

Mesonacis eagerensis — photo 1 — Photo 1 · Holotype UBC GT101 (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Caron et al., 2023)

Mesonacis eagerensis — photo 2 — Photo 2 · Holotype UBC GT101 (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Caron et al., 2023)

Mesonacis eagerensis — photo 3 — Photo 3 · Holotype UBC GT101 (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Caron et al., 2023)

Mesonacis eagerensis — photo 4 — Photo 4 · Holotype UBC GT101 (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Webster et al., 2024) (Canada; Caron et al., 2023)

Classification

Order Redlichiida / Suborder Olenellina / Superfamily Olenelloidea / Family Olenellidae

Genus

Mesonacis Walcott, 1885

Genus author

Walcott C. D.

Genus etymology

meso, Greek, middle; nacis, spear.

Species

M. eagerensis (Best, 1952)

Species author

Best R. V.

Species etymology

Eager, from the Eager Formation of the Cranbrook area, British Columbia, Canada, the type locality of this species.

Age

Cambrian, Series 2, Stage 4

Distribution

Canada

Synonyms

Olenellus eagerensis; Olenellus (Olenellus) eagerensis

Diagnosis

Cephalon roughly pentagonal, genal spines slender and long, border narrow and convex; glabella constricted at S1, with three pairs of glabellar furrows; preglabellar field absent; posterior margin of occipital ring with small node; palpebral lobe crescentic; genal ridge present; also occur. Prothorax: 14 segments; each axial ring with a small axial node on its posterior margin; 3rd segment macropleural, pleural spines slender and long; pleural spines of the 13th and 14th segments long spine-like; pleural furrow broad, extending extending onto the pleural spine; 15th segment with a long axial spine, comparable in length to the pleural spines of the 13th and 14th segments. The rest of the thorax and pygidium are unknown.