Ammonite ID

[Rockchopper]

Just acquired this ammonite and am hoping someone can tell me more about it and where it might have come from.  I believe somewhere in South Dakota, but not sure.  Thanks in sdvance.

[doushantuo]

Looks slightly scaphitid,but undoubtedly someone will come along who is able to determine ammo's in his/her sleep 

Closeup of the suture line* might help

*the thin squiggly lines transversely crossing the shell

[doushantuo]

Landman's reply to the article I posted a while back.If irrretrievable:I'll post it again

landmaneyv067.pdf

[PFOOLEY]

Here is a link to Scaphitid ammonites of the Upper Cretaceous (Maastrichtian) Fox Hills Formation in South Dakota and Wyoming. Bulletin of the AMNH ; no. 215...should be quite useful in your search for a name.

[Rockchopper]

Just want to thank those that replied to my query about my ammonite.  The link by PFOOLEY was extremely helpful.  I've found this forum to be very welcoming and the members eager to help. For someone like me with limited knowledge about fossils, this site is invaluable.  Thanks again.

[RJB]

That,,, is one beautiful Scaphite!!!

 

RB

[Rockchopper]

Thanks!  Its about 3.5 inches and am still trying to zero in on the species, but am leaning towards Jeletzkytes nebrascensis.  Hopefully more knowledgable folks can enlighten me more!

[doushantuo]

Then it would be a Hoploscaphites species

Ammonite revisions are many,you see

JeletskyItes(riccardi,1983) has been revised

[Rockchopper]

Why Hoploscaphites? 

So now I'm confused.

Ricarrdi, 1983, describes Jeletzkytes as a genus of scaphatoid.  He states that it resembles the genus Scaphites and says it includes J. Nebrascensis and 6 others. 

So is it a Scaphites or a Scaphatoid?  And how can one tell the difference?

 

[Rockchopper]

As I learn more, and know less, why the genus Hoploscaphites and not genus Jeletzytes?  What differentiates the two genus that allows an identification on my ammonite?

[doushantuo]

I understand your confusion.

edit:

I think i might have found it :(Landman,2010,AMNH bull 342)

"Traditionally, the more robust, more coarsely ornamented scaphites (comprising the "nodosus group") from the Pierre Shale and Bearpaw Shale were assigned to Jeletzkytes Riccardi, 1983, and the more slender, more finely ornamented scaphites were assigned to Hoploscaphites Nowak, 1911. However, our large collections of these scaphites from the Baculites compressus– B. cuneatus zones reveal a complete intergradation between the two morphological extremes, and for many specimens, the choice of genus is arbitrary. In addition, our studies of other biostratigraphic zones in the Pierre Shale and Bearpaw Shale reveal that cooccurring species of these two "genera" share more in common with each other than they do with congeneric species from other horizons. Furthermore, contrary to earlier assumptions, Jeletkytes is not endemic to the Western Interior Basin of North America and occurs, for example, in the U.S. Atlantic Coastal Plain and Europe. We thus provisionally treat Jeletzkytes as a junior subjective synonym of Hoploscaphites."

 

What does this  mean?.

Well,in my own words,if Riccardi had had the material ,back in 1983,that Landman et al  had around 2010 or so,he might have called it Hoploscaphites.

Species discrimination in paleontology is much more difficult  than it is in the study of Recent material.

It is greatly helped by having lots of specimens /material to study).

On the basis of a greater amount of material,paleontologists can develop a better view of the way characters are distributed in time and space,and the possible interrelations between characters.Did the ornament change as the animal got older,or the shell shape?And how about the suture line?

 

 

Just let me know if i haven't been clear enough.

I know the tinyiest bit about the Mollusca,but there are a lot of people here with a far greater amount of hands-on knowledge of ammonite taxonomy.

Pfooley provided a link about Scaphitidae which might contain their definition.

Those definitions are clothed in technical language,BTW

They always are.

Perhaps a user friendly ammonite recognition site might be found on the Net?

I haven't tried to find one ,BTW

 

 

 

 

[Rockchopper]

That helps quite a bit and explains why Hoploscaphites is preferred.  Now to narrow the Genus to species.  I'm guessing that might be more problematic without very detailed analysis. I really appreciate the time and effort you spent answering this for me.  Thanks!

[doushantuo]

well ,it it weren't for some football/"Soccer" coming up and a VERY empty stomach(the neighbours might start to complain about the rumbling),I might have tried to help you right now,but a body's gotta eat,right?

I've got some good scaphitid stuff by Monks,which is a kind of short review.

edit: i hate to leave like that,here it is,stomach be da**n**

J. Mollus. Stud.-2000-MONKS-205-16.pdf

i have to warn you: the style is technical,it's a "trade journal" so to speak

Always glad to be of help ,ofcourse

[Rockchopper]

I understand the need to eat!   Appreciate yhe link.  Have a great 4th!

[Baculites]

The ammonites is a microconch of Hoploscaphites nebrascense from the H. nebrascense biozone. Its likely from the Trail City Member of the Fox Hills Formation in north central South Dakota. Also the issue over what genus this belongs to is meaningless. Some authors want to do away with genera completely because they are not evolutionary defined but instead defined by an arbitrary ranked based system of classification chosen by an authors personnel choice.