Does anybody recognize this ammonite?

[FossilDAWG]

The other day I bought a set of ammonites from a dealer who was selling off specimens from an old collection.  Two of the ammonites were labeled, probably correctly, as the Triassic species Ceratites nodosus and Acanthoceratites spinosus.  A third specimen was also labeled as a ceratitid, but it is clearly different.  For example the suture line is not at all ceratites-like, and is definitely an ammonite.  To my eye several features suggest Placenticeras, a late Cretaceous genus.  These include a flat venter with alternating clavi (elongated nodes), nodes at about mid flank, possible faint umbilical nodes, and a very complex suture line.  If it is a Placenticeras it doesn't exactly match the species I am familiar with, and the preservation is also unfamilar.  Note that there is a lot I don't know about the genus.  However it occurs to me that various species of Placenticeras are found in Europe.  Of course, it also could be something else entirely.  I am asking the community, and especially my fellow ammonite aficionados ( @rocket @Ludwigia @PFOOLEY et al) if they recognize the species and/or the mode of preservation.  

 

General aspect:

 

 

Flank with nodes:

 

 

 

Venter showing flat edge with clavi (elongated nodes) on either side:

 

 

Suture line:

 

 

I forgot to get a photo of the profile with the aperture, I will add that this evening when I get home.

 

Don

 

 

 

[JohnJ]

@Heteromorph

 

In the meantime, compare to Placenticeras syrtale as a possibility.

[caterpillar]

I think that Placenticeras is more oxycone

[Ludwigia]

I'm afraid that I can't be of much help here since I'm not really up on my cretaceous ammonites, although I can at least definitely confirm that this is not a ceratite.

[rocket]

great pics, let me take some time in the evening to compare

Do not know for 100% now but think I can identify next day 

Definitely cretaceous, was wrong with my first idea that it´s a jurassic one

[Heteromorph]

Compare with Placenticeras intercalare.

 

I found a similar (but heavily crushed) ammonite in the late Coniacian of the Austin Chalk (last picture).

 

See also: 1, 2, 3, 4

[rocket]

I would agree to Placenticeras cf. intercalare

I am not absolutely sure, but do not know, why. It´s the "nose" we say in Germany. You feel something but cannot justify. Very cool preservation, never seen one in this condition before, and I love cretaceous fossils since decades...

[FossilDAWG]

Thanks all for the suggestions.  John, I agree that Placenticeras syrtale is very close.  This specimen is a bit more involute than my P. syrtale specimens from Alabama, but they are a little flattened which might distort the umbilicus a bit.  Placenticeras intercalare is also close.  The illustrations I have found show specimens with the shell, and mine is a steinkern, which complicates comparison.  Placenticeras intercalare has more prominent umbilical nodes and stronger ribbing, but that could easily be due to the shell vs internal mould issue.  I'll post again when/if I get it figured out.

 

Don

[PFOOLEY]

What a great specimen of Placenticeras, Don...excellent acquisition! 

 

Due to the nodes, P. interclare and P. syrtale are good starting points but my S.W.A.G. would be Placenticeras costatum...they too carry similar ornament, but it is not as pronounced. 

 

@Foshunter has some great P. syrtale from the Blossom Sand to use as a reference.

[PFOOLEY]

@FossilDAWG, here are some snapshots for reference...

 

   

 

...from this paper...

 

A survey of the Cretaceous ammonite PlacenticerasMeek, 1876, in the United States Western Interior.pdf

 

...on Placenticeras from the Western Interior. 

[FossilDAWG]

Thanks Mike.  That is quite useful.  One potential complication is that the specimen came without provenance (actually, with the wrong label) from an old collection that contained both European and North American fossils.  There are some European Placenticeras that are very similar to some North American species such as Placenticeras syrtale, so I have to run down literature on those too.  Unfortunately there was a very nice web site on French ammonites that was shut down recently in protest against new French restrictions on collecting.  That could have been useful.

 

Don

[Heteromorph]

On 1/26/2023 at 6:52 PM, FossilDAWG said:

Thanks Mike.  That is quite useful.  One potential complication is that the specimen came without provenance (actually, with the wrong label) from an old collection that contained both European and North American fossils.  There are some European Placenticeras that are very similar to some North American species such as Placenticeras syrtale, so I have to run down literature on those too.  Unfortunately there was a very nice web site on French ammonites that was shut down recently in protest against new French restrictions on collecting.  That could have been useful.

 

Don

The French site is still accessible. https://web.archive.org/web/20220523180601/http://www.ammonites.fr/

[FossilDAWG]

Thank you so much!  That website is a fantastic resource.  So much work went into building it.

 

Don

[Heteromorph]

On 12/13/2022 at 5:35 PM, Heteromorph said:

Compare with Placenticeras intercalare.

 

I found a similar (but heavily crushed) ammonite in the late Coniacian of the Austin Chalk (last picture).

 

See also: 1, 2, 3, 4

For the record, it now seems my specimen shows more affinities to Forresteria brancoi.

 

https://geoweb.princeton.edu/archival/keller/Stinnesbeck-2005-Revista.pdf