Agnostida

Tomagnostus fissus

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Ptychagnostidae

Cambrian, Miaolingian Wuliuan to DrumianSweden, Denmark, Canada

Tomagnostus fissus — photo 1 — Photo 1 · Cephalon neotype SGU 4840 (Sweden; Whittington et al., 1997) Illustrated specimens (Denmark; Weidner et al., 2014) Illustrated specimens (Canada; Hildenbrand et al., 2021)

Tomagnostus fissus — photo 2 — Photo 2 · Cephalon neotype SGU 4840 (Sweden; Whittington et al., 1997) Illustrated specimens (Denmark; Weidner et al., 2014) Illustrated specimens (Canada; Hildenbrand et al., 2021)

Tomagnostus fissus — photo 3 — Photo 3 · Cephalon neotype SGU 4840 (Sweden; Whittington et al., 1997) Illustrated specimens (Denmark; Weidner et al., 2014) Illustrated specimens (Canada; Hildenbrand et al., 2021)

Classification

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Ptychagnostidae

Genus

Tomagnostus Howell, 1935

Genus author

Howell B. F.

Genus etymology

tom-, Greek, cut; Agnostus, a trilobite genus name.

Species

T. fissus (Lundgren in Linnarsson, 1879)

Species author

Lundgren

Species etymology

fissus, Latin, split, cleft.

Age

Cambrian, Miaolingian Wuliuan to Drumian

Distribution

Sweden, Denmark, Canada

Synonyms

Agnostus fissus; Agnostus fissus trifissus; Ptychagnostus (Ptychagnostus) fissus

Diagnosis

Cephalon and pygidium suboval. Cheek of cephalon with sparse furrows; glabellar frontal lobe nearly trapezoidal with distinct anterior pit; F3 inverted V-shaped, posterior lobe stout-cylindrical; preglabellar median furrow incompletely developed; basal basal lobe small. Pygidium smooth; pygidial axis stout; postaxial median furrow weak; F1 inverted V-shaped, F2 V-shaped; median node on M2; posterior axial ring with transverse depression; no marginal lateral spines.

Remarks

This species is the type species of Tomagnostus.