Skip to content Skip to navigation

Article: Some lesser known features of the ancient cephalopod order Ellesmerocerida (Nautiloidea, Cephalopoda)

Publication: Palaeontology
Volume: 50
Part: 3
Publication Date: May 2007
Page(s): 565 572
Author(s): Björn Kröger
Addition Information

How to Cite

KRÖGER, B. 2007. Some lesser known features of the ancient cephalopod order Ellesmerocerida (Nautiloidea, Cephalopoda). Palaeontology50, 3, 565–572.

Online Version Hosted By

Wiley Online Library
Get Article: Wiley Online Library [Pay-to-View Access] |


Three specimens of the small breviconic ellesmeroceratid Paradakeoceras minor Flower, 1964 from the Tremadocian of the New York area preserve the annular elevation and muscle scars in moulds of the body chamber. The annular elevation is positioned at the base of the body chamber and is wider on the convex side of the shell than on the concave side. Multiple paired muscle scars can be seen within this annular elevation. A well-preserved body chamber of the breviconic ellesmeroceratid Levisoceras cf. edwardsi Ulrich, Foerste and Miller is described. Its body chamber shows a strong anterior-posterior asymmetry, which is common within the Ellesmeroceratida. The shape of the body chamber and of the soft body attachment structures has led to a reconstruction of an ellesmeroceratid soft body that is organized like a primitive conchiferan mollusc. Based on this reconstruction, a tryblidian cephalopod ancestor is supported. An evolutionary scenario is reconstructed from an ancestral nautiloid that is stretched along the anterior-posterior axis, and has serially arranged shell muscles and a small mantle cavity, towards a modern cephalopod with a dorsal-ventral body orientation, reduced number of shell muscles and a large mantle cavity.
PalAss Go! URL: | Twitter: Share on Twitter | Facebook: Share on Facebook | Google+: Share on Google+