Agnostida

Aspidagnostus laevis

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Clavagnostidae

Cambrian, Miaolingian, GuzhangianHunan, Zhejiang; USA

Aspidagnostus laevis — photo 1 — Photo 1 · Holotype specimen USNM 143130 (USA; Palmer 1962) Illustrated specimens (Hunan; Peng Shanchi 2020) Complete dorsal shield Complete dorsal (Zhejiang; Guodong) shield, part and counterpart (3.5 mm, Zhejiang; Tang Shi)

Aspidagnostus laevis — photo 2 — Photo 2 · Holotype specimen USNM 143130 (USA; Palmer 1962) Illustrated specimens (Hunan; Peng Shanchi 2020) Complete dorsal shield Complete dorsal (Zhejiang; Guodong) shield, part and counterpart (3.5 mm, Zhejiang; Tang Shi)

Aspidagnostus laevis — photo 3 — Photo 3 · Holotype specimen USNM 143130 (USA; Palmer 1962) Illustrated specimens (Hunan; Peng Shanchi 2020) Complete dorsal shield Complete dorsal (Zhejiang; Guodong) shield, part and counterpart (3.5 mm, Zhejiang; Tang Shi)

Aspidagnostus laevis — photo 4 — Photo 4 · Holotype specimen USNM 143130 (USA; Palmer 1962) Illustrated specimens (Hunan; Peng Shanchi 2020) Complete dorsal shield Complete dorsal (Zhejiang; Guodong) shield, part and counterpart (3.5 mm, Zhejiang; Tang Shi)

Aspidagnostus laevis — photo 5 — Photo 5 · Holotype specimen USNM 143130 (USA; Palmer 1962) Illustrated specimens (Hunan; Peng Shanchi 2020) Complete dorsal shield Complete dorsal (Zhejiang; Guodong) shield, part and counterpart (3.5 mm, Zhejiang; Tang Shi)

Classification

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Clavagnostidae

Genus

Aspidagnostus Whitehouse, 1936

Genus author

Whitehouse F. W.

Genus etymology

aspi-, Greek, shield, armour; Agnostus, a trilobite genus name.

Species

A. laevis Palmer, 1962

Species author

Palmer A. R.

Species etymology

laevis, Latin, smooth.

Age

Cambrian, Miaolingian, Guzhangian

Distribution

Hunan, Zhejiang; USA

Synonyms

Aspidagnostus inquilinus; A. actuosus; A. taoyuanensis ?Aspidagnostus primitivus; ?Aspidagnostus orientalis

Diagnosis

Cephalon rounded-square, middle of anterior margin slightly protruding; glabella short, sublanceolate, anterior end pointed; preglabellar median furrow deep and complete; basal lobe large, triangular; with a pair of posterolateral spines. Pygidium part pentagonal; F1 and F2 of the pygidial axis weak, M2 constricted medially forming a cross with the median node; posterior axial ring with a pair of deep pits behind the median node; terminal end of the pygidial axis sharply pointed, extending to border furrow; pygidial border widening inward with a bow-tie-like swelling medially; with a pair of posterolateral spines and a median spine.

Remarks

Typical body length about 0.2-0.6 cm.