Agnostida

Agnostus pisiformis

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Agnostidae

Cambrian, Miaolingian, GuzhangianSweden, Norway, Denmark, UK, Canada

Agnostus pisiformis — photo 1 — Photo 1 · Cephalon lectotype, PM Vg819a, b (Sweden; Whittington et al., 1997) Reconstruction (Müller et al., 1987) Famous ventral-structure reconstruction (Müller et al., 1987) Orsten-type phosphatized three-dimensional structures (Sweden; Müller et al., Famous reconstruction model (Eriksson et al., 1987) 2017)

Agnostus pisiformis — photo 2 — Photo 2 · Cephalon lectotype, PM Vg819a, b (Sweden; Whittington et al., 1997) Reconstruction (Müller et al., 1987) Famous ventral-structure reconstruction (Müller et al., 1987) Orsten-type phosphatized three-dimensional structures (Sweden; Müller et al., Famous reconstruction model (Eriksson et al., 1987) 2017)

Agnostus pisiformis — photo 3 — Photo 3 · Cephalon lectotype, PM Vg819a, b (Sweden; Whittington et al., 1997) Reconstruction (Müller et al., 1987) Famous ventral-structure reconstruction (Müller et al., 1987) Orsten-type phosphatized three-dimensional structures (Sweden; Müller et al., Famous reconstruction model (Eriksson et al., 1987) 2017)

Agnostus pisiformis — photo 4 — Photo 4 · Cephalon lectotype, PM Vg819a, b (Sweden; Whittington et al., 1997) Reconstruction (Müller et al., 1987) Famous ventral-structure reconstruction (Müller et al., 1987) Orsten-type phosphatized three-dimensional structures (Sweden; Müller et al., Famous reconstruction model (Eriksson et al., 1987) 2017)

Agnostus pisiformis — photo 5 — Photo 5 · Cephalon lectotype, PM Vg819a, b (Sweden; Whittington et al., 1997) Reconstruction (Müller et al., 1987) Famous ventral-structure reconstruction (Müller et al., 1987) Orsten-type phosphatized three-dimensional structures (Sweden; Müller et al., Famous reconstruction model (Eriksson et al., 1987) 2017)

Classification

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Agnostidae

Genus

Agnostus Brongniart, 1822

Genus author

Brongniar A.

Genus etymology

agnost-, Greek, unknown

Species

A. pisiformis (Wahlenberg, 1818)

Species author

Wahlenberg G.

Species etymology

pisi-, Greek, pea;-formis, shaped like

Age

Cambrian, Miaolingian, Guzhangian

Distribution

Sweden, Norway, Denmark, UK, Canada

Synonyms

Entomostracites pisiformis; Agnostus (Agnostus) pisiformis; Agnostus pisiformis pisiformis; Agnostus pisiformis dissimilis; Agnostus pisiformis spiniger; Agnostus pisiformis subsulcatus; Agnostus procerus; Agnostus pisiformis vastificus; Agnostus (Agnostus?) confusus; Agnostus (Agnostus) distinctus

Diagnosis

Cephalon and pygidium almost round. Glabella cylindrical, divided into three segments, frontal lobe subpentagonal; median node long, at the front of the posterior lobe; glabellar transverse furrow straight; preglabellar median furrow distinct; basal lobe triangular; Border furrow broad and deep; border narrow. Thorax of two segments. Pygidial axis divided into three rings, second ring with stout axial node, posterior axial ring large; border furrow broad and deep; border narrow; with a pair of small posterolateral spines.

Remarks

Agnostus pisiformis is the type species of Agnostus; its ventral soft-part structures have been thoroughly studied thanks to Orsten-type exceptional preservation in Sweden.