Warburgoceras, Kröger, 2013

Kröger, Björn, 2013, The cephalopods of the Boda Limestone, Late Ordovician, of Dalarna, Sweden, European Journal of Taxonomy 41, pp. 1-110 : 82-83

Genus Warburgoceras gen. nov.

urn:lsid:zoobank.org:act:7BD9C0A9-AFD0-4AD8-B910-BFC3E32AD603

Type species

Cyrtoceras longitudinale Angelin in Angelin & Lindström, 1880 , Kallholn, Dalarna, Sweden, Boda Limestone, Boda Core Member, late Katian, Ordovician; by montotypy.

Diagnosis

Continuously expanding gyrocones with circular, slightly compressed or slightly depressed cross section; angle of expansion in premature stages ca. 13°, decreasing during growth; ornamented with fine, irregularly spaced growth lines that form broad, shallow sinus on convex side of conch and with fine irregularly spaced longitudinal striae; mature body chamber with only weak terminal constriction; sutures straight and nearly directly transverse, with shallow lobe on prosiphuncular side of conch; ca. 4–5 chambers per distance similar to corresponding conch height; siphuncle eccentrically positioned, with SPR of ca. 0.1 at convex side of conch curvature; siphuncular segments slightly expanded within chamber, siphuncle diameter ca. 0.09 of corresponding conch cross section; connecting ring thin; septal necks short, loxochonoanitic-suborthochoanitic.

Etymology

In honor of Elsa Warburg (1886–1953), a Swedish paleontologist who published her doctoral thesis on the trilobites of the Boda Limestone ( Warburg 1925) and collected most of the cephalopods of the Boda Limestone during the first decades of the 20 th Century.

Remarks

The position and shape of the siphuncle and the longitudinal ornamentation are characters that are typical of the Uranoceratidae and justify an assignment of this new genus within this family.

Comparison

Deckeroceras Foerste, 1935 from the late Katian Fernvale Formation of Oklahoma is most similar to Warburgoceras gen. nov. in general conch shape, but the body chamber is more inflated in the former, the siphuncle is more expanded and less eccentric, and the features of the external shell are not known. It is possible that Warburgoceras gen. nov. is a subjective junior synonym of Deckeroceras . However, since no details of the external shell are known from the latter and the types of both genera differ in some details, Warburgoceras gen. nov. is erected herein.

Warburgoceras gen. nov. differs from Uranoceras Hyatt, 1884 in having a nearly circular conch cross section, non-lobate, directly transverse sutures and in beeing more openly curved.

Stratigraphic and geographic range

Boda Limestone, late Katian, Dalarna, Sweden.

Species included

Type species only.