Cyrtogomphoceras Foerste, 1924

Kröger, Björn, 2025, The Lyckholm acme of cephalopods - Review of the late Katian (Vormsi-Pirgu regional stages) Ordovician cephalopods of Estonia, European Journal of Taxonomy 978, pp. 1-169 : 100

Genus Cyrtogomphoceras Foerste, 1924

Type species

Oncoceras magnum Whiteaves, 1890 , East Selkirk, Selkirk Member, Red River Formation, late Katian, Ordovician, by original designation

Diagnosis

Compressed endogastric cyrtocones with fusiform outline in lateral view; rapidly expanding in adoral part of mature phragmocone and/ or basal part of mature body chamber; mature body chamber gibbous, conically contracted; aperture with hyponomic sinus; sutures with shallow lateral lobes, sloping increasingly toward the antisiphuncular side of the conch in later growth stages; siphuncle large, not strictly marginal, with short cyrtoconic septal necks, thick connecting rings, and endosiphuncular bullettes, cameral deposits absent. (Adopted from Teichert 1964b.)