Which one is this?

[Azemiops]

I'm an amateur fossil hunter (stumble across, pick up) and need a pro's help. I've found a bunch of these "ammonites" and I can't find them in books. I'm a bit of a stickler when it comes to classification, and I would like to put a real name to these. This is one of the larger ones I've come across. P.S. Sorry for the lousy quality of the photo

 

[Ludwigia]

It's often not possible to classify an ammonite just on the basis of a piece of the outer whorls, but if you could try to at least get your photo in focus, then maybe @PFOOLEY could take a stab at it.

[Max-fossils]

@Ludwigia makes a good point. Try taking better photos, and people will surely be able to help you. 

 

Also, it would be really useful if you said where you found this ammonite piece, otherwise coming up with an ID is definitely impossible. 

 

Max

[Miocene_Mason]

It is an ammonite piece, shortly sone local pros will probably give a guess or to (this is assuming that is from New Mexico)

[Azemiops]

No, this is from a river in Roanoke Texas. The riverbed is all clay, and there are fossils of all kinds every couple of inches or so. All the little things are pretty easy to identify. But, this species is always eluding me. The problem is, they are either missing the inner spiral or they don't have one. They all just seem to end in this little tail thing. Because they all look the same, I assumed that this is how they are supposed to look.

 

 

[abyssunder]

I think one possibility could be that it is a worn Mortoniceras fragment. It will be useful to have an image showing the keel.

[Azemiops]

That  Mortoniceras does look like the small ammonites I've found along side these. They are all intact! Only the big ones, like the one in the photo, are incomplete. That's why I'm so confused. All the big ones look the same, and all the big ones look like this. Is that unusual?

 

 

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[Douvilleiceras]

The ammonite-containing rocks surrounding the city of Roanoke are Cretaceous. These Mesozoic rocks turn out to represent both Upper and Lower Cretaceous epochs, and both have a diverse ammonite fauna. The genus Mortoniceras (from the Albian age, Lower Cretaceous) is recorded in the Main Street Limestone formation, which surrounds Roanoke, making it a definite possibility. Graysonites, a similar ammonite from the same superfamily, is found in neighboring formations that date from the Cenomanian, as is Stoliczkaia, 

and due to the fragmentary nature of the specimen in question, it may be difficult to make a definitive assignment of genera. However, due to the general lack of a dorsal keel on specimens of the latter two genera, I think it is most likely Mortoniceras.

 

Source:

 J. Kennedy, W & A. Cobban, W & M. Hancock, J & Gale, Andy. (2005). Upper Albian and Lower Cenomanian ammonites from the Main Street Limestone, Grayson Marl and Del Rio Clay in northeast Texas. Cretaceous Research - CRETACEOUS RES. 26. 349-428. 10.1016/j.cretres.2004.11.018.