Need help identifying this Ammonite fossil

Ahh! the species level ID, now this is where the fun starts. :biggrin2:

Things to take into account; 1) Ontogenetic changes, looking at a few other specimens here, it looks like the larger they get the smoother they get, the early whorls have many ribs the later whorls are smooth, at what ontogenetic stage is the specimen in question? 2) Dimorphism, is this a macroconch or a microconch, female or male, how much overlap in ornamentation is there between the two dimorphs? Between the dimorphs of different species? 3) Intraspecific variation, how much variation in the ornamentation occurs in this species, does the rib strength and spacing vary from one specimen to another? 4) Stratigraphic position, how do these change over time, does the ornamentation of a younger species match that of an older species at a different ontogenetic stage? 5) Anthropogenic modification, many fossils have been ground and polished to make them look nice, how many diagnostic characters have been ground or polished away?

The above is mostly considering the ornamentation, if the suture lines were visible we would have to look at all of this as it applies to the suture as well.

:read:This is the point where we go to the library and find all the literature on Cleoniceras and study it for a few years. Or take it to someone who has already done the research and let them ID it. Or wish the collector would have had it ID'd and put a label on when it was collected. Seeing all the specimens for sale on the web you'd think that someone would have a better ID.

Of course you could just post a photo on TONMO and hope for the best :sly:
 
This one comes somewhat close, but is alas merely labeled Cleoniceras sp. :sad:

Cleoniceras_2.jpg
 
So, this would be C. madagascariense; a close contender?

cleoniceras%20madagascariense.jpg


And this C. besairei


cleoniceras%20besairiei%202.jpg


I think here, the ribbing is again a bit more compact and decisively more regular than in your specimen.
 
Again, C. madagascariense.

FS%204427.jpg


Would this rule out Morocco?

Edit: I do realize many Madagascar fossils enter the marketplace via Moroccan traders.
 
Haha well this is extremely complex. Alas, Cleoniceras sp. may be as good as it gets. Thanks for your help. Does the book Ammonites by Monk have good reconstructions of ammonites? I imagine you have the book or at least have perused it, Architeuthoceras.

I have a quick question for those of a taxonomic mind. I have seen, most recently at the Georgia Aquarium for a graphic on the Manta rays Manta ssp. I imagined sp to stand for species, and ssp subspecies, but the graphic said that the mantas had been redivided into multiple species of an unknown taxonomic classification.

By the way, I really like taxonomy! It is kind of a weird interest not shared by many, but I love the order and universality.
 
Ah, I did not see that there was a second page to this discussion.

Kevin, the last image you have shown looks very, very similar to the other ammonite fossils the store had. Now, it may be somewhat of a chancy leap to assume that they all came from the same place, but it is a possibility!
 
I still think C. besairei is inconsistent with this specimen's ribbing, but who am I? :wink:

The splicing is what gives it away as C. madegascariense, as far as I'm concerned, but please, correct me!
 
It does look rather like this guy's Cleoniceras madagascariense: Cleoniceras (Cleoniceras) madagascariense

It's a little hard to tell in that last link, but the Aioloceras looks like its longer ridges are spaced a little bit differently than your specimen and are united into little V's at the umbilicus rather than staying separate. Unclear whether this is more significant than the aforementioned difference from Cleonoceras, though.
 

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