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Cyrtodiscus evolvens

Gastropoda - Bellerophontida - Sinuitidae

Taxonomy
Cyrtolites evolvens was named by Perner (1903) [Cyrtolites? evolvens Barrande in Perner 1903]. It is a 3D body fossil.

It was recombined as Temnodiscus evolvens by Horný (1963) and Marek (1963); it was recombined as Pharetrolites evolvens by Peel (1977); it was recombined as Cyrtodiscus evolvens by Horný (1997), Horný (2002), Ebbestad et al. (2013) and Wagner (2017).

Synonymy list
YearName and author
1903Cyrtolites evolvens Perner p. 88 figs. pl. 86 f. 22-24
1963Temnodiscus evolvens Horný pp. 91 - 92 figs. pl. 15 f. 1-5
1963Temnodiscus evolvens Marek p. 280
1977Pharetrolites evolvens Peel p. 14
1997Cyrtodiscus evolvens Horný p. 45
2002Cyrtodiscus evolvens Horný pp. 73, 86 figs. pl. 1 f. 15
2013Cyrtodiscus evolvens Ebbestad et al. p. 15 figs. 7F-L
2017Cyrtodiscus evolvens Wagner p. S2392

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Spiralia
superphylumLophotrochozoa
phylumMollusca
RankNameAuthor
classGastropodaCuvier 1797
orderBellerophontidaUlrich and Scofield 1897
suborderBellerophontina
superfamilyBellerophontoidea()
familySinuitidae
genusCyrtodiscus()
speciesevolvens()

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
J. O. R. Ebbestad et al. 2013Shell small, up to 8 mm long, narrow lenticular, with acute dorsum. Whorl width slightly less than one-third of whorl height. The periphery is in the lower third of the whorl. Three whorls are present, being slightly involute with about half the height of earlier whorls embraced. Sutures slightly incised. Ornamentation consists of densely but evenly spaced, slightly undulating transverse lirae. These are fine and sharp but become thicker and more rib-like in late ontogeny. Finer growth lines are not visible in between the sharper lirae. Spiral ornamentation is expressed as faint lines in the interspace between the growth ribs. The apertural lip is not thickened, gently and evenly prosocyrt, curving back medially to form a V-shaped sinus of unknown depth. The angle to dorsum is less than ∼30◦. The sinus culminates in a slightly raised dorsal crest at the dorsum. At the umbilical wall the apertural lip is adpressed in late ontogeny to form a subsutural sinus.