Kevin Cummings asked about Devonian Gonioceras from Morocco.

Gonioceras Hall, 1847 is a large, straight-shelled actinoceratoid
cephalopod. The Treatise on Invertebrate Paleontology (part K, p. K208)
gives this diagnosis by Curt Teichert (1964):

"Large shells, ventral side rather flat, dorsal side moderately convex, 2
sides meeting laterally at acute angle; aperture contracted; sutures with
broad dorsal and ventral lobes, more narrowly rounded dorsolateral and
ventrolateral saddles and pointed lateral lobes. Siphuncle subcentral;
septal necks armenoceroid, brims very short; segments short;
endosiphuncular canal system straight. Cameral deposits rare." Range:
Middle Ordovician, North America, Europe, Eurasia (Urals and perhaps East
Asia). Some of these features can only be seen in section, i.e., by slicing
the specimen. Which experts on fossil cephalopods do very frequently.

The diagnosis for family Gonioceratidae Hyatt, 1884 is slightly more
comprehensible:

"Large, straight shells, strongly depressed in cross section, with flat
ventral and dorsal sides and angular flanks; sutures sinuous. Siphuncles
comparatively small, subventral to subcentral." Range: Middle to Upper
Ordovician.

As the actinoceratoids ranged from Middle Ordovician to Upper
Carboniferous, I suspect that these Devonian fossils have been
misidentified, but may belong to the same order.

Andrew K. Rindsberg
Geological Survey of Alabama