Dowlingoceras Foerste, 1928d

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 : 70

Genus Dowlingoceras Foerste, 1928d

Type species

Poterioceras gracile Whiteaves, 1892 , Black Island, Swampy Harbour, Lake Winnipeg, Manitoba, Canada, Red River Formation, Katian; by original designation.

Diagnosis

Slender diestoceratids with straight or slightly curved shell, and elliptically compressed to oval conch cross section; mature body chamber with widest height and width near its base, with simple constriction close to mature aperture, with apertural widening and shallow hyponomic sinus; siphuncle positioned near conch margin, with, compared to other diestoceratids, narrow septal foramen and only slightly expanding segments. (Compiled from Teichert 1930, and Sweet 1964b.)

Comparison

Danoceras and Dowlingoceras differ mainly in the shape of the siphuncular segments (i.e., subtrapezoidal versus fusiform, respectively, Strand 1934: 80). In the Estonian material, a difference in the shape the mature body becomes also apparent: in Dowlingoceras , it is relatively long (ratio height / length ca one or more) and simple convex, while Danoceras has an adorally constricted, amphora-like body chamber.