Advice on 3 unknown cephalopod fossils

[ntloux]

I have three cephalopod fossils in my collection with little to no background information. 

 

The first two photos are of a specimen collected in Kentucky by a family member (presumably near Berea). 

The smaller cephalopods on the upper right and left in Photo 1 compare very favorably with Gomphoceras images. 

The larger samples in Photo 2 show middle indentations with reduced chambers and septa; possibly indicative of hard times in the paleozoic. 

 

 

 

 

Photos 3 and 4 are of specimens acquired from the liquidation of the former Emerald Rock Shop in Deer Park, Ohio (the owners had passed on).  There is no background information on these specimens but they do compare favorably with Ceratites based on the shapes of the "ribs' near the keel and the thinness of the specimens. 

 

 

 

 

Photo 5 is a specimen that was mislabeled as a brachiopod.  It compares favorable with images of imported Acanthoceras specimens from Morocco.

 

 

I would greatly appreciate constructive comments and/or suggestions concerning these specimens.

 

Sincerely,  Nick Loux

Gomphoceras1.pdf Gomphoceras2.pdf Ceratite1.pdf Ceratite2.pdf Acanthoceras.pdf

[Ludwigia]

The first ones do look like Gomphoceras and I would also concur on the Acanthoceras, but I'm not so sure about the ones in the middle, since those whorls could stem from any number of ammonites from cretaceous back to jurassic and not only triassic ceratites. I don't think there's enough material there without the provenance to establish a definite id even down to the family.

[Bringing Fossils to Life]

The "nautiloids" (a possibly useless group, considering that the name has been used for three groups in the past couple hundred years and it should only refer to one of them) in picture 2 appear to have long, curved constructions only because of the way they were cross sectioned; cephalopods do not shrink, but they do attain much more discrete constrictions at maturity.

 

 

[Ludwigia]

19 hours ago, Bringing Fossils to Life said:

The "nautiloids" (a possibly useless group, considering that the name has been used for three groups in the past couple hundred years and it should only refer to one of them) in picture 2 appear to have long, curved constructions only because of the way they were cross sectioned; cephalopods do not shrink, but they do attain much more discrete constrictions at maturity.

 

 

Just curious to learn more. Which 3 groups are you talking about?

[Bringing Fossils to Life]

A study from a couple years ago (Early cephalopod evolution clarified through Bayesian phylogenetic inference) suggested that Nautiloidea should be split into three main groups: Endoceratoidea, Multiceratoidea (Nautiloidea), and Orthoceratoidea (also includes Ammonoidea and Coleoidea). These groups are monophyletic, and Ellesmocerida is found to be polyphyletic, as genera from this group were spread over the three subclasses. I thought that I posted this before, but cannot find the post anywhere. Below is a phylogeny of the entirety of Cephalopoda, more inclusive and accurate than my previous attempt. I have cited the major resources I used at the bottom; the icons (36 in all) are based off of dozens of pictures. I believe this to be the first time the order Yanhecerida was been illustrated.

[Ludwigia]

Well, as far as I'm concerned, if this is just another suggestion, then I'll still continue to call these things Nautiloids as long as the expression is still being utilized in recognized current works or until the Treatise or some other authority decides to debunk the subclass Nautiloidea. There was an in-process revision relatively recently on the subject. By the way @Bringing Fossils to Life  you seem to be quite knowledgeable, but it would interest me to hear if any of your works have been peer reviewed.

[Bringing Fossils to Life]

None of my works have been peer reviewed; my research and reconstructions are simply a hobby that has grown in the past years.