Ammonite from Rom, France

[Max-fossils]

Hello again,

 

Here another fossil that I bought at the same time as the shell in the previous topic.

It's an ammonite coming from Rom, near Tours, in France; and the age of it is around 185mya (Pliensbachien stage of the early Jurassic).

The seller did noot know what species it was exactly, but he was thinking of possibly Harpoceras sp.

If yes, then what species of Harpoceras  is it? If no, what is it then?

 

Best regards,

 

Max

[Max-fossils]

The back:

 

[Max-fossils]

And the width of the fossil (maybe useful):

 

[FossilDAWG]

How confident are you about the seller's information?  This ammonite does not look like a Harpoceras to me, or any Jurassic ammonite I know of.  Indeed it has a strong resemblance to some common Late Cretaceous genera, such as Hoplites, Sphenodiscus, or perhaps Placenticeras, although the suture lines don't look placenticerid from what I can see of them.  Also the matrix/mode of preservation seems typical of many Cretaceous formations.  However I do not know the Jurassic of the Roms area so it is possible that I am simply ignorant of Jurassic ammonites of this aspect.

 

Don

[TqB]

If Pliensbachian, could well be Tragophylloceras. (Sutures look phylloceratid but I'm no ammonite expert.)

I think Harpoceras is just Toarcian.

[Max-fossils]

1 hour ago, FossilDAWG said:

How confident are you about the seller's information?  This ammonite does not look like a Harpoceras to me, or any Jurassic ammonite I know of.  Indeed it has a strong resemblance to some common Late Cretaceous genera, such as Hoplites, Sphenodiscus, or perhaps Placenticeras, although the suture lines don't look placenticerid from what I can see of them.  Also the matrix/mode of preservation seems typical of many Cretaceous formations.  However I do not know the Jurassic of the Roms area so it is possible that I am simply ignorant of Jurassic ammonites of this aspect.

 

Don

Hi Don,

 

The seller's info is most probably wrong, as he knew a lot more in minerals than in fossils. The only thing he was sure about was that the ammonite comes from Rom in France. But the genus was just a wild guess, and the age is rather approximate too. Of course, it may very well be that the location is wrong too. Maybe @fifbrindacier could help.

 

Thanks for your help,

 

Max

[Max-fossils]

35 minutes ago, TqB said:

If Pliensbachian, could well be Tragophylloceras. (Sutures look phylloceratid but I'm no ammonite expert.)

I think Harpoceras is just Toarcian.

Thanks for your help! Tragophylloceras does indeed seem like a suitable option.

 

Max

[marguy]

hello,

if this can help... (i don't know this site but searched on french geological service)

Rom is about 140km South Tours (seller said near Tours!) and 40km south west Poitiers, near Couhé.

here is local geological map , you can see NW of Rom village  a quarry, in lower-median oxfordian;   

notice writes:

• L'Oxfordien inférieur n'a été identifié qu'en un seul point au Sud de la feuille, à Rom, où un mince niveau conglomératique d'l à 2 cm d'épaisseur,  discontinu, recouvre la surface supérieure taraudée des calcaires calloviens. Il a livré Cardioceras sp.,une ammonite d'âge Oxfordien inférieur.

 and more , for the country, lower and medio Oxfordian

 les ammonites sont particulièrement nombreuses. On peut ainsi reconnaître de bas en haut: Cardioceras (Cawtoniceras) tenuiserratum, Dichotomosphinctes buckmanni, D. antecedens (zone à Plicatilis, sous-zone à Antecedens), Ochetoceras canaliculatum, Proscaphites anar, Subdiscosphinctes richei, Gregoryceras transversarium, Neomorphoceras col/inti (zone à Transversarium, sous-zone à Parandieri), Larcheria prelothari, L. subschilli, Trimarginites arolicus, Passendorferia sp. (zone à Transversarium, sous-zone à Schilli), Dichotomoceras bifurcatus, D. bifurcatoides, D. stenocycloides, D. grossouvrei (zone à Bifurcatus).

[Ludwigia]

At first glance, I thought immediately upper Jurassic. Judging from the form, it could very well be a Streblites sp., which occurs from the Kimmeridgian up into the Tithonian. I would however need more fosussed photos in order to better judge.

[Ridgehiker]

This specimen can't be identified though an image.  One needs to know the strata it was found in and then examine the suture lines.  There are literally hundreds of Mesozoic ammonite species from France.

 

i collected extensively in the French Mesozoic ( thousands of specimens) and still could not give a visual ID without the info above.

 

The cephalopods and brachiopods of the Mesozoic in France provide what may be the most extensive window macro fauna biostratigraphy in the world. 

 

For example this is a small part of my France ammonite collection and my collection is just a fraction of potential taxa. Not one specimen could be identified without drawing out the suture pattern and using a research source to compare it to.

 

 

[Ludwigia]

I would however recognize a Strebltes if it was pictured properly.

 

[Max-fossils]

Hi @marguy, @Ludwigia and @Canadawest,

 

Thanks all very much for your help!

@Ludwigia, Streblites does indeed seem like a good possibility.

And @Canadawest, what a great collection! But looking closely at the ammonites you have posted there, not many look very similar to mine, so I think finding the species (or at least the genus) just with the pictures might be "do-able". And from the list of @marguy, I think the best possibility is: Trimarginites arolicus.

But for some clearer pictures, I fear we might have to wait till Thursday next week, when I'll be with my fossils again...

 

Best regards,

 

Max

[Ludwigia]

Trimarginites is also a very good possibility, although I wouldn't go as far as trying to name the species. Like I said, better photos would certainly help.

[Max-fossils]

2 minutes ago, Ludwigia said:

Trimarginites is also a very good possibility, although I wouldn't go as far as trying to name the species. Like I said, better photos would certainly help.

I know, but unfortunately we will have to wait till Thursday next week...

 

Thanks for your help

[fifbrindacier]

On 5 décembre 2016 at 5:45 PM, Max-fossils said:

Hi Don,

 

The seller's info is most probably wrong, as he knew a lot more in minerals than in fossils. The only thing he was sure about was that the ammonite comes from Rom in France. But the genus was just a wild guess, and the age is rather approximate too. Of course, it may very well be that the location is wrong too. Maybe @fifbrindacier could help.

 

Thanks for your help,

 

Max

Thanks for quoting me Max, but i am sorry, i am not an ammonite expert. But if you come in the region one day, i'd be glad to hunt ones with you.

[Max-fossils]

Just now, fifbrindacier said:

Thanks for quoting me Max, but i am sorry, i am not an ammonite expert. But if you come in the region one day, i'd be glad to hunt ones with you.

So would I! Only Landes is quite a bit of a "détour"...

I usually go to Tourves (near Aix-en-Provence, or Eggs-en-Provence for the fossil-lovers) every summer, and sometimes we hunt there.

But I am sure you're far better in ammonites than I am, the only species I can immediately recognize is Cleoniceras (well, sometimes Promicroceras too, but that's really IT.)

 

Best regards,

 

Max

[fifbrindacier]

16 minutes ago, Max-fossils said:

So would I! Only Landes is quite a bit of a "détour"...

I usually go to Tourves (near Aix-en-Provence, or Eggs-en-Provence for the fossil-lovers) every summer, and sometimes we hunt there.

But I am sure you're far better in ammonites than I am, the only species I can immediately recognize is Cleoniceras (well, sometimes Promicroceras too, but that's really IT.)

 

Best regards,

 

Max

The only ammonites i am able to recognize are the ones i see on a list of fossils of where i am (with few names on it) and with really neat photos to compare with. I'd really like to hunt in Eggs-en-Provence one day.

[Ridgehiker]

Eggs-en-Provence.

 

Reminds of collecting down in Texas.  A researcher in the group was a student from a 

Texas university and another guy kept calling him an 'Eggie'.  Finally I asked why their university was named after a chicken.  He wasnt saying Eggie but Aggie which was short for 'Agriculture'

[Max-fossils]

11 hours ago, fifbrindacier said:

I'd really like to hunt in Eggs-en-Provence one day.

So would I, but I'm not sure whether there's a site open for public...

[fifbrindacier]

12 hours ago, Canadawest said:

Eggs-en-Provence.

 

Reminds of collecting down in Texas.  A researcher in the group was a student from a 

Texas university and another guy kept calling him an 'Eggie'.  Finally I asked why their university was named after a chicken.  He wasnt saying Eggie but Aggie which was short for 'Agriculture'