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Is this Dactylioceras or Perisphinctes?


Sagebrush Steve

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Sagebrush Steve

Hi Everyone,

 

I purchased this ammonite from a shop in Colorado several years ago.  The only identification they provided was that it was an ammonite from Morocco.  I believe them because the opening has been cut flat and filled in like ammonites from Morocco typically are.  I have tentatively identified it as a Dactylioceras but I'm not sure, another possibility could be Perisphinctes.  There also could be other possibilities, too.  Since I don't have information on where it was collected, I don't know what age it comes from.  I think I read an older post on this forum that the ribs on Dactylioceras only split in two, but on Perisphinctes they sometimes split into three, but I haven't been able to find that post again (Ludwigia, I seem to remember you were the one who made that comment).  This one looks like some of the ribs split into 3, which might suggest Perisphinctes.  Also I've included a photo showing a suture line, which I understand can be used to make an identification, but I haven't found anything on the web that gives examples of suture lines for different families.  Can anyone help with the identification?   Thanks for the help, this forum is amazing!

Dactiloceras 1.jpg

Dactiloceras 2.jpg

Dactiloceras 3.jpg

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I think this Perishinctes is from Madagascar, Jurassic.

  • I found this Informative 2
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Sagebrush Steve

Thanks abyssunder, that is the post I was trying to find again.

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Sagebrush Steve

Thanks doushantuo, those are two very useful papers.  As for the correct spelling of Dactylioceras, I have seen it spelled both ways in various posts here on this forum and throughout the Internet.  Thanks for showing the correct spelling.

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Looks like Abysunder beat me to the punch again :ammonite01:

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I've just rechecked. The proper spelling of the valid subgenus is Prososphinctes(Schindewolf), not Prosososphinctes. Maybe that would help sort out any confusion which may arise.

The thing with the Perisphinctidae is that there are a lot of possibilities to choose from, for instance Divisosphinctes besairi or Dichotomosphinctes antecedens. If in doubt, a simple Perisphinctes sp. would suffice.

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Prosophinctes was misspelled, I agree.
Perisphinctes (Prososphinctes) virguloides (Waagen) = Prososphinctes virguloides (Waagen) might be the correct name.
Unfortunately the primary reference H. Besairie and M. Collignon. 1972. Geologie de Madagascar I. Les Terrains Sedimentaires. Annales Geologiques de Madagascar 35:1-463  is not available online (at least for me).

Here is nice site with lots of ammonites for comparative reason: http://jsdammonites.fr

 Madagascar

Prososphinctes virguloides (Waagen)

 

PERISPHINCTES+sp+102mm+Oxfordien+Madagascar+L$2BV.jpg

 

 

 

 

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I've got a bit of Collignon,but no taxonomy(the Argovian- Rauracian atlas part(IV) shows P Virguloides.

Collignon on D.Besairie:

Fig. 350. DIVISOSPHINCTES BESAIRIEI nov. Sp. TYPE (1 ), 0.102- -H : 0, 035(0. 34.); E : 0; 031. (0, 30), -O; 0,045. (0-44).
- Côtes 42. Comparée à D. bifurcartus Qu. cette belle espèce en diffère par le nombre des côtes plus considérable,
les flancs moins plats, l'existence d'une magnifique et profonde constriction terminale. La disposition
des côtes est identique et leur point de bifurcation placé au même endroit. Exemplaire complet avec apophyse
jugale; jusqu'ici inconnue dans le genre Cloison du type Divisosphinctes à lobe latéral court et à éléments
auxiliaires très réduits. Je genre est uniquement rauracien (en Europe) ; il me permet de rapporter à cet
étage le gisement d'Antrobika ainsi que ceux de Bepea et Maroroka : leurs faunes sont identique et diffèrent
de celles de l'Argovien supérieur sous-jacent à Liogryphea par l'absence totale des Mayaitidae. Rauracien Gisement
370, Antrobika (Sakaraha), Coll. M. Collignon, 1954

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i take it the Siemiradski I posted is totally useless?

Edit:

the Glowniak revison in Volumina Jurassica,would that be useful?

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Sagebrush Steve

I have corrected the spelling of Dactylioceras in the posting title and keywords.  There are links to many excellent resources here and I would like to make sure this comes up when people do a search.  And I agree, the photos I originally posted look consistent with Perisphinctes sp., which is as far as I would take it.

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Sagebrush Steve
21 hours ago, doushantuo said:

Gygi1998.pdf

Whatever it is,it's not Dactyloceras.

Dactylioceras,perhaps?

I've been reading this paper and it's very interesting.  My specimen is about 70mm diameter and I count 42 ribs in the last whorl.  All of the species in the paper have more like 60 ribs per whorl at 70mm diameter.  So mine wouldn't be any of the listed species.  I think there might be some correlations in the Malinowska paper you also provided (Arisphinctes?).  In any event I'm learning a lot.  Also, the Gygi paper made the following comment about how measurements were made; any chance you have Figure 16 from the Cecca & Enay paper?  I wouldn't need the whole paper, I just want to make sure I am doing my measurements correctly.  Thanks.

Gygi paper.JPG

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