One cephalopod ID

[Fossillife300]

So here's another cephalopod. It is fairly small. We have a tentative ID of loganoceras. We got that idea from reading Wilson's document but not from anyone with more experience. This specimen is from Paquette area. Any input would be really valuable, thanks!

[Fossillife300]

We thought for example it has a similar curve to the end pieces of these ones from the Wilson document, but we are not experts... Thanks!

 

[Fossildude19]

@FossilDAWG

 

Don (FossilDAWG) has quite a bit of experience with fossils from your area.

Hopefully he can weigh in with his practical experience.

[FossilDAWG]

Loganoceras is a possibility, but there are similar genera such as Richardsonoceras.  The distinction is in the cross-sectional shape.  Loganoceras is essentially circular, and Richardsonoceras is flattened on the sides so it has an oval cross section.  I have some specimens much like yours, and without prepping them further or sectioning them to reveal their cross section I can't confidently ID them.

 

BTW I have found Steele & Sinclair 1971 "A middle Ordovician fauna from Braeside, Ottawa Valley, Ontario; GSC Bulletin 211" (pdf available here) to be more useful than Wilson's publications, although I use them too.  Steele & Sinclair synonymized several of the Loganoceras species listed in Wilson's cephalopod memoir, as they showed that those "species" were actually just fragments from different parts of the shell with slightly different curvature and rates of expansion.  Wilson was well known to be a "splitter", describing lots of new species based on small variations.  As well, her various volumes on the Ottawa "Formation" faunas listed uncritically all the various species described by earlier workers.  August Foerste and later Rousseau Flower described many cephalopods from the Ottawa area and especially Paquette Rapids, and they were both (especially Foerste) extreme splitters who used any difference no matter how small to name new species.  When more complete material can be found, it often turns out that the early growth stages are different from the mature or older shell, and fragments of different parts of the shell have been given different names.  I have thought that re-evaluating the cephalopods and other taxa, based on new and larger samples from Paquette Rapids would be a good thesis project for someone.

 

Do you have access to the Paquette Rapids area?  I only visited there once, by canoe, as I did not find a way to access by land.  I also made a fairly large collection from Steele's Braeside locality, but I think that site has been developed now.

 

Don

[Fossillife300]

Thank you for your expertise! That's helpful to hear because a lot of them do look quite similar. We've had our trilos identified previously but the cephalopods are much much trickier. Especially if all of the dimensions aren't visible. I'll have a look too at the other document you suggested!

 

Unfortunately, we don't do collecting anymore so I'm not up to date on the sites. Our fossils are from years ago, some 20 years ago. Once in awhile though we go through our rocks to see if there's something new we can learn from the ones we have. 

 

Thanks so much again for discussing the cephalopods, it's always great to chat fossils!