Agnostida

Geragnostus sidenbladhi

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Metagnostidae

Ordovician, Early Ordovician TremadocianSweden, Norway

Geragnostus sidenbladhi — photo 1 — Photo 1 · Pygidial lectotype SGU25; Sweden (Whittington et al., 1997) Illustrated specimens (Sweden; Ahlberg 1989) Reconstruction (Zhou Zhiyi Illustrated specimens (Norway; Ebbestad 1987) 1999)

Geragnostus sidenbladhi — photo 2 — Photo 2 · Pygidial lectotype SGU25; Sweden (Whittington et al., 1997) Illustrated specimens (Sweden; Ahlberg 1989) Reconstruction (Zhou Zhiyi Illustrated specimens (Norway; Ebbestad 1987) 1999)

Geragnostus sidenbladhi — photo 3 — Photo 3 · Pygidial lectotype SGU25; Sweden (Whittington et al., 1997) Illustrated specimens (Sweden; Ahlberg 1989) Reconstruction (Zhou Zhiyi Illustrated specimens (Norway; Ebbestad 1987) 1999)

Geragnostus sidenbladhi — photo 4 — Photo 4 · Pygidial lectotype SGU25; Sweden (Whittington et al., 1997) Illustrated specimens (Sweden; Ahlberg 1989) Reconstruction (Zhou Zhiyi Illustrated specimens (Norway; Ebbestad 1987) 1999)

Classification

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Metagnostidae

Genus

Geragnostus Howell, 1935

Genus author

Howell B. F.

Genus etymology

ger, from Greek geron-, old, old man; Agnostus, a trilobite genus name.

Species

G. sidenbladhi (Linnarsson, 1869)

Species author

Linnarsson J. G. O.

Species etymology

Sidenbladh, a surname.

Age

Ordovician, Early Ordovician Tremadocian

Distribution

Sweden, Norway

Synonyms

Agnostus sidenbladhi

Diagnosis

Cephalon and pygidium nearly square; border furrow broad and deep; border broad. Glabellar transverse furrow weakly V-shaped, with long median node beneath; basal lobe small, triangular. Pygidial axis subparallel-sided, divided into three rings, Anterior two rings transversely tripartite by median node; Median node prominent, arising from first axial ring, extending to front of terminal segment; With a pair of pygidial lateral spines.

Remarks

This species is the type species of Geragnostus.