Ammonite Id

[plsurfer]

I found this beauty out hunting last year, wondering if anyone of you paleo can help my ID what type of ammonite it is, I have not been able to find a similar specimen online or through contacts anywhere.

IMG_8172 by bwallrich07, on Flickr

Edited February 24, 2013 by plsurfer

[FossilDAWG]

It is quite important to give some information about the age, geological formation, and an approximate locality when asking for an ID. Assuming you found this somewhere in Utah, ammonites (including ceratites types) might be found in Devonian, Mississippian, Pennsylvanian, Permian, Triassic, Jurassic, and Cretaceous rocks, with many different species at each level. Knowing the age and formation will reduce the possibilities a lot. Also, your specimen seems to be pretty weathered, so the appearance of the suture lines may be quite different from the fresh shell surface. Is there any unworn shell exposed on the other side of the specimen, and if so could you post a photo? Also, an edge-on view would be useful, to give an idea of the cross-sectional shape of the shell.

Don

[plsurfer]

It is quite important to give some information about the age, geological formation, and an approximate locality when asking for an ID. Assuming you found this somewhere in Utah, ammonites (including ceratites types) might be found in Devonian, Mississippian, Pennsylvanian, Permian, Triassic, Jurassic, and Cretaceous rocks, with many different species at each level. Knowing the age and formation will reduce the possibilities a lot. Also, your specimen seems to be pretty weathered, so the appearance of the suture lines may be quite different from the fresh shell surface. Is there any unworn shell exposed on the other side of the specimen, and if so could you post a photo? Also, an edge-on view would be useful, to give an idea of the cross-sectional shape of the shell.

Don

Thanks fossilDAWG, I don't have that much information but It was found in south east Idaho in the preuss range (just east of Montpelier) at around 8500ft at the very top of the mountain laying on the ground exposed exactly as you see it. other than that I dont have much more information.

[Auspex]

I'm pretty impressed with the as-found state of this fossil; sure looks nice!

[squalicorax]

Alot of early triassic up that way, could be Meekoceras sp

[plsurfer]

Alot of early triassic up that way, could be Meekoceras sp

looking at some info online, the closest place that lists ammonites is soda springs area triassic, thaynes limestone, where I found this one was 20 miles south of soda springs, on the top of the hill, so it couldn't have been deposited from anywhere, this summer I plan on returning to the site, marked in my GPS with some tools to investigate further... its a LONG hike

http://www.fossilsites.com/STATES/ID.HTM

Edited February 24, 2013 by plsurfer

[sixgill pete]

Wow, that is very cool. Great find in my book. Sorry, but can't help you with an ID though.

[plsurfer]

I did happen to find something similar in this book

http://books.google.com/books?id=937lAAAAMAAJ&pg=PA93&dq=ammonites+montpelier+idaho&hl=en&sa=X&ei=8a0qUcmkIdGvigLl_4GQDg&ved=0CDwQ6AEwAg#v=onepage&q=ammonites%20montpelier%20idaho&f=false

On page 92/93 figure 44/45 meckoceras mushbachlanum?

Edited February 27, 2013 by plsurfer

[plsurfer]

anyone else have an opinion about this article?

[Mr_ed]

I have .. I think it about the coolest fossil I have seen found as it. Flip it over so we can see the other side please..

Ed

[BobWill]

I think you've made a good ID there. I thought the same as Don at first because ammonites with more elaborate sutures often wear down to straighter parts of the septum that can look similar to what you have, but if a species can be found there with those simple sutures That's probably what you have. Can you see enough of the other side to tell if the whorl profile is uniform?

[plsurfer]

IMG_8374 by bwallrich07, on Flickr

Photo 1, the fatter lower part is where the "entrance" would be

IMG_8372 by bwallrich07, on Flickr

Photo 2: another view of the "entrance"

IMG_8370 by bwallrich07, on Flickr

Photo 3: the reverse side.

I would also like to restate that this was found 20 miles from the closest known exposure with ammonites, and those being only half the size of this one from what research I have done.

Edited February 27, 2013 by plsurfer

[BobWill]

Yep, the profile matches too. The similar M.gracilitatis has a slightly different suture.

[plsurfer]

Yep, the profile matches too. The similar M.gracilitatis has a slightly different suture.

now the question is.... are there more in the area that could be complete? it seems unlikely that this one floated to the top of the mountain by iteslf....flat part at the tip top of a mountain...no similer rocks around though... start digging?

any thoughts about that?

[BobWill]

now the question is.... are there more in the area that could be complete? it seems unlikely that this one floated to the top of the mountain by iteslf....flat part at the tip top of a mountain...no similer rocks around though... start digging?

any thoughts about that?

I never dig unless I can see an exposed part of a fossil worth going in after. Look for places where a lot of rock is showing to increase the chances one of them could be a fossil...creeks, washes, road cuts, etc.

Also look on a geo map to see if the formation 20 miles away may be the same as what's on your mountain.

Edited February 27, 2013 by BobWill

[BobWill]

I couldn't find a geo map for Idaho on line but I see the Thaynes Limestone mentioned in the Mansfield paper in western Wyoming on the clickable geological map at the bottom of the page here<br />http://ngmdb.usgs.gov/Prodesc/proddesc_16366.htm<br />

Edited February 27, 2013 by BobWill

[Auspex]

This beauty shows years of weathering; the question is how much of the fossiliferous layer remains. This could be the tip of the iceberg, the last one that hasn't become gravel, or something in between. I prescribe a recon

[BobWill]

I would also like to restate that this was found 20 miles from the closest known exposure with ammonites, and those being only half the size of this one from what research I have done.

That "fossil sites" page you provided a link to is not exhaustive enough to reliably say there shouldn't be ammonites where you found this one. Most of the information is from decades ago and most finds are not recorded there. Suqailcorax suggested the same genus you found the picture of in the Mansfield paper and the sutures seem to match those in the picture so if you want more of that ammonite you should be looking for that Thaynes Formation in other places. It may be that the formation plays out at the top of your mountain but if you don't find M.mushbachlanum you might look for the other fossils on the same page as they should also appear in the Thaynes. Try reading the text starting on the bottom of page 87 to get an idea of where else to look. Edited February 28, 2013 by BobWill

[plsurfer]

That "fossil sites" page you provided a link to is not exhaustive enough to reliably say there shouldn't be ammonites where you found this one. Most of the information is from decades ago and most finds are not recorded there. Suqailcorax suggested the same genus you found the picture of in the Mansfield paper and the sutures seem to match those in the picture so if you want more of that ammonite you should be looking for that Thaynes Formation in other places. It may be that the formation plays out at the top of your mountain but if you don't find M.mushbachlanum you might look for the other fossils on the same page as they should also appear in the Thaynes. Try reading the text starting on the bottom of page 87 to get an idea of where else to look.

ya I read that, I did go back up and was unable to find any rock material matching this fossil from the base of the mountain to the top, it was in a depression at the top of the hill where the snow does sit longer than surrounding areas, this spring i plan on investigating this depression a bit more as it could be eroding the tip of the formation.... well have to wait and see... I do appreciate all the input from everybody, I will keep you all posted this spring on how the search goes as this was an amazing find for me, and the possibility of finding more or ann even better one is to great for the location this one was found in. rocks dont fly... unless you throw them

[FossilDAWG]

Rocks may not fly, but they can sometimes walk. Nice obvious cool-looking fossils (which yours certainly is) have turned up at archeological sites. For example, an excellent trilobite was found at an archeological site in the Frazer Valley in British Columbia; the only possible source is the Tanglefoot Creek area near Cranbrook, also in British Columbia but several hundred miles to the East, across a few big mountain ranges. It's not impossible that your specimen may have been transported by people as a sort of talisman. Or, it might have eroded out of the rock at the site, in which case you should be able to find matching rock material.

By the way, your profile photos do suggest that the specimen is significantly eroded on the side that shows sutures, so those sutures are probably quite different (i.e. a lot more simple) than they would be on the actual surface of the shell. To get a better view of the original surface, it looks like you might be able to clean up more of the surface on the uneroded side. On the other hand, if this is an archeological object (an artifact), altering it would damage it. Personally, I'd leave it as is, at least until you know whether or not it originated on the mountain top where you found it.

Don

[Boneman007]

I found a great Britton formation crab from Dallas in the Niobrara formation of Western Kansas once. Clearly I had pulled my bagpack out of the back of my truck the year before, and accidently dropped a crab from a previous Dallas hunt.

I also remember a incedent at a Dallas Paleo Society meeting where a member had found miocene shark teeth at a pennsylvannian site. Everyone thought he was lying. Turned out a member of the Dallas Museum of Natural History had thought it would be good to "seed" the site before taking young students there. You guessed it, He used miocene shark teeth!

Fossils do get dropped, and sometimes purposely placed where they shouldnt be.

I would be surprised if a ammonite this nice was purposely discarded, though. I sure wouldn't have thrown it away!

[Indy]

Rocks may not fly, but they can sometimes walk .............

Don

True !!

Many years ago, a local fossil enthusiast who was also

a practical joker ... would sometimes "plant" fossils he

found form different time periods at known fossil hunting sites.

Then laugh when someone mentioned they found something

never before reported from a formation or time period.

[BobWill]

By the way, your profile photos do suggest that the specimen is significantly eroded on the side that shows sutures, so those sutures are probably quite different (i.e. a lot more simple) than they would be on the actual surface of the shell.

Don

To me it looks more worn on the side with some matrix still attached. Did you look at the sutures on the ammonite in the paper plsurfer offered a link to in his post #8? It's at the bottom of the page with line drawings after page 92 or 93. The sutures on it look exactly like what shows on his fossil and it's found in a formation very near the area his was found.

edit: Also notice the profile view in those line drawings, it's a good match for the good side of this ammonite. If you look at the 1st profile photo plsurfer posted, at the top where there's no matrix on either side, and draw an imaginary line down the venter, notice how much thicker it is on the side with sutures than the side with matrix on the bottom.

Edited March 1, 2013 by BobWill

[FossilDAWG]

Bob, I repectfully disagree. I don't see how it would be possible to be thicker on the unweathered side, where you can see shell in the photos, than it is on the worn side with the sutures. If you look at the profile view you can see the smooth rounded profile on the side with some matrix still attached, and an abrupt change to a more flattened and somewhat irregular (not smoothly rounded) profile on the side with the sutures. It seems clear to me that at least a few mm has been removed on the suture side. Indeed I suspect the specimen has been worn past the venter, except for a bit right where the last whorl overlaps the previous one.

It's remarkable how much the sutures "simplify" with a little erosion. All the "frilly bits" are right at the surface, take off a mm or so from the most complicated sutures and you get something that is a lot simpler, becoming ceratite-like and even nautilus-looking when you get down to the cross section. These images (off the web) of Madagascar ammonites show how the suture changes from very light polishing (basically just removal of the shell) in image 1, through very light grinding removing a fraction of a mm (image 2), to deeper grinding and finally sectioning. As far as I can tell, these are all the common Madagascar ammonite Cleoniceras.

Now, the specimen in question may well be a Meekoceras from the Thaynes, I'm not saying that it isn't. I just think we have to be careful we don't base the ID on a profile and suture that is altered by being worn down.

Don

[BobWill]

Yeah Don, I see what you mean about the 2nd profile picture. I was focusing on the top of the 1st picture where it looks quite a lot thicker on the side without matrix near the venter. You're also right about the look of septa worn past the suture, I have several I keep to help explain that feature to new collectors. You're also, also right about IDs without knowing the formation and no collector should expect anything but suggestions until they are able to look up their site on a geo map or ask locally. The combination of sutures (if that's what they are) and profile shape being such a good match with Squalicorax's original suggestion and the effort plsurfer made to find that line drawing probably had me really wanting that to be a good ID. Let this be a lesson to us all

Edited March 4, 2013 by BobWill