Pennsylvanian brachiopod and ammonite

[BobWill]

Good idea John. We're very lucky so many of them go to the trouble. Maybe your encouragement is paying off.

edit: Looking closer at the image in that paper, Neodimorphoceras sp. has an arched venter which is sometimes grooved, and the larger of your fossils has a much more rounded venter ( figure 10 and 11, plate 32). If the immature shells can have ribs that disappear later as in Gonioloceras sp. than maybe it's Imitoceras sp. after all. I don't like to disagree with the experts though, so maybe Dr. Mapes can explain what I'm seeing wrong.

Edited November 26, 2015 by BobWill