Agnostida

Tsunyidiscus acutus

Order Agnostida / Suborder Eodiscina / Superfamily Eodiscoidea / Family Tsunyidiscidae

Cambrian, Series 2, Stage 3Hubei

Tsunyidiscus acutus — photo 1 — Photo 1 · Cranidium (holotype) and its external Ontogenetic sequence reconstruction (Dai mould YY201, 202 (Hubei; Sun Zhenhua et al., 2011) 1983) (Hubei; Lin Tianrui et al. 2004) Illustrated specimens NWUJT 20206-12, 20214 (Hubei; Dai et al., 2011)

Tsunyidiscus acutus — photo 2 — Photo 2 · Cranidium (holotype) and its external Ontogenetic sequence reconstruction (Dai mould YY201, 202 (Hubei; Sun Zhenhua et al., 2011) 1983) (Hubei; Lin Tianrui et al. 2004) Illustrated specimens NWUJT 20206-12, 20214 (Hubei; Dai et al., 2011)

Tsunyidiscus acutus — photo 3 — Photo 3 · Cranidium (holotype) and its external Ontogenetic sequence reconstruction (Dai mould YY201, 202 (Hubei; Sun Zhenhua et al., 2011) 1983) (Hubei; Lin Tianrui et al. 2004) Illustrated specimens NWUJT 20206-12, 20214 (Hubei; Dai et al., 2011)

Tsunyidiscus acutus — photo 4 — Photo 4 · Cranidium (holotype) and its external Ontogenetic sequence reconstruction (Dai mould YY201, 202 (Hubei; Sun Zhenhua et al., 2011) 1983) (Hubei; Lin Tianrui et al. 2004) Illustrated specimens NWUJT 20206-12, 20214 (Hubei; Dai et al., 2011)

Tsunyidiscus acutus — photo 5 — Photo 5 · Cranidium (holotype) and its external Ontogenetic sequence reconstruction (Dai mould YY201, 202 (Hubei; Sun Zhenhua et al., 2011) 1983) (Hubei; Lin Tianrui et al. 2004) Illustrated specimens NWUJT 20206-12, 20214 (Hubei; Dai et al., 2011)

Classification

Order Agnostida / Suborder Eodiscina / Superfamily Eodiscoidea / Family Tsunyidiscidae

Genus

Tsunyidiscus Chang, 1966

Genus author

Zhang Wentang

Genus etymology

Tsunyi, Zunyi, Guizhou; discus, disc.

Species

T. acutus (Sun, 1983)

Species author

Sun Zhenhua

Species etymology

acutus, sharply pointed, referring to the narrow-conical glabella.

Age

Cambrian, Series 2, Stage 3

Distribution

Hubei

Synonyms

Hupeidiscus acutus; Hupeidiscus jingshanensis; Hupeidiscus nitidus

Diagnosis

Glabella narrow-conical, anterior margin pointed, with two broad, shallow crossing glabellar furrows; occipital ring with an occipital spine projecting backward and upward; anterior border broad and gently convex; anterior border furrow broad and shallow; palpebral lobe long; eye ridge slightly convex; fixed cheek broad and convex, with genal spines. Thorax of three segments, axis with nodes; pleural region widening gradually backward. Pygidial axis convex, terminal end not reaching the posterior border, divided into three axial rings and one terminal segment, each axial ring with nodes; pleural region without pleural or interpleural furrows; border furrow broad and shallow.