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ammonite genus ID?


ober

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Hello all, I have what I believe to be a segment of an ammonite. I think this is in the Acanthoceratidae family. I can see the suture patterns very clearly. This piece is 15 mm long and was found in Mancos Shale near Moab. In ID-i got it I find the Cretaceous Atlas of Ancient Life particularly helpful. So first, am I on the correct track so far? If so, then I wonder how I can I go to the genus level of identification. I am looking at the robustness of the ridge pattern and see it is common with Acanthoceras, but there are other possibilities as well. Does an incomplete sample like this allow you to make a genus identification or not? Or is the best you can do make a probability statement, such as it is this or that? What specifically about this segment should I focus on to get to the next level and what source would you recommend for this type of identification? Is the key in the suture patterns? Thanks for your help. Tom

A16E2FA3-44D1-4C87-92C9-0B753C2A3EB8.jpeg

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I suspect you are on the right track.  However @PFOOLEY is very familiar with the ammonites in that area and he should be able to offer a more authoritative opinion.

 

Don

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I am not completely familiar with the Mancos Shale and its ammonite fauna, but to me it matches with Prionocyclus, probably P. hyatti, a member of the Acanthoceratoidea superfamily. It would help to see different angles like the venter i.e. top and the dorsum i.e. underside of the specimen, as well as other angles. But from finding Acanthoceras amphibolum in the Texas Tarrant formation I can tell you that this looks very different from that genus. However, more pictures may prove me wrong. It also depends on where you are stratigraphically in the Mancos, something which PFOOLEY would be able to help you with. 

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2 hours ago, Heteromorph said:

I am not completely familiar with the Mancos Shale and its ammonite fauna, but to me it matches with Prionocyclus, probably P. hyatti...seeing different angles like the venter i.e. top and the dorsum i.e. underside of the specimen, as well as other angles would help. But from finding Acanthoceras amphibolum... I can tell you that this looks very different from that genus...

Agreed. :ammonite01:

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"I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?"  ~Aldo Leopold (1887-1948) 

 

New Mexico Museum of Natural History Bulletins    

 

point.thumb.jpg.e8c20b9cd1882c9813380ade830e1f32.jpg research.jpg.932a4c776c9696d3cf6133084c2d9a84.jpg  RPV.jpg.d17a6f3deca931bfdce34e2a5f29511d.jpg  SJB.jpg.f032e0b315b0e335acf103408a762803.jpg  butterfly.jpg.71c7cc456dfbbae76f15995f00b221ff.jpg  Htoad.jpg.3d40423ae4f226cfcc7e0aba3b331565.jpg  library.jpg.56c23fbd183a19af79384c4b8c431757.jpg  OIP.jpg.163d5efffd320f70f956e9a53f9cd7db.jpg

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Thank you all. I will search for a better image of Prionocyclus to see if I can see what you are seeing. This is, as you can tell, new to me. Tom

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Is the key you have been looking at to ID this as Prionocyclus the spacing between the ridges? And the sharpness of the ridges? Thanks. Tom

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@ober, you can download a good paper here...

 

http://digitallibrary.amnh.org/handle/2246/514

 

... :).

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"I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?"  ~Aldo Leopold (1887-1948) 

 

New Mexico Museum of Natural History Bulletins    

 

point.thumb.jpg.e8c20b9cd1882c9813380ade830e1f32.jpg research.jpg.932a4c776c9696d3cf6133084c2d9a84.jpg  RPV.jpg.d17a6f3deca931bfdce34e2a5f29511d.jpg  SJB.jpg.f032e0b315b0e335acf103408a762803.jpg  butterfly.jpg.71c7cc456dfbbae76f15995f00b221ff.jpg  Htoad.jpg.3d40423ae4f226cfcc7e0aba3b331565.jpg  library.jpg.56c23fbd183a19af79384c4b8c431757.jpg  OIP.jpg.163d5efffd320f70f956e9a53f9cd7db.jpg

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Hello pfooley, thanks so much. This will take some time to digest but looking ahead to the prionocyclus section I think I can see clues in the spacing of the ridges. I will print this for easier reading. Just a quick glance has helped me with another embedded fossil, which I realize is an ammonite spine. Over more than I decade I developed a nice library to help me with medieval French coinage and now I see I am going to be doing the same with marine inverts. I think here the sources are as likely to be online as actual printed books. Tom

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