Lieber Volker, sieht aus wie ein großer Ostracode, Gigantocypris muelleri erreicht auch eine Größe von 3 cm. Herzlich, Volker

Lieber Volker,

gute Idee - der Form nach könnte dies zutreffen! Aber ich denke, mein Fossil ist zu groß (Länge: 4,5 cm!) für einen Ostracoden der Gattung Gigantocypris. Mal schaun, ob noch weitere Infos/Vorschläge hierzu eintreffen?

Bis demnächst mit herzlichen, kollegialen Grüßen;

Volker aus SIG 

Lieber Volker, die größten rezenten Vertreter von Gigantocypris erreichen auch 33 mm, die größten fossilen Formen wie Leperditia werden bis 60 mm und mehr angegeben. Volker aus TH

Hallo Volker,

Ich denke es handelt sich um einen Koprolithen. Koprolithen dieser Größe und Form kommen in manchen Plattenkalkfundstellen recht häufig vor. Die gefalteten Strukturen am Rand entstehen durch Schrumpfungsprozesse bei der Diagenese.

Beste Grüße,

Martin

Hallo Volker,

Die Identifizierung als Koprolith von Martin Ebert kann ich gut nachvollziehen. Ein Ostracode ist dies gewiss nicht.

Gruß Günter

Vielen Dank Volker, Martin u. Günter,

Koprolith kann ich ebenfalls gut nachvollziehen! Denn:

- keine Hartteile (zB Calcit-Material) überliefert, nur Positiv-Abdruck, 

- relative weiche ehem. Konsistenz (ersichtlich aus den lateralen "Falten", die wohl postsedimentär entstanden durch Sedimentauflast und/oder Schrumpfungsprozesse).

- annähernd ovaler, ei-förmiger Umriss.

Kann man da evtl. Aussagen über den Verursacher des potenziellen Koprolithen machen (evtl. anhand der Form und "Punktierungen" auf der konvexen Oberfläche)? Muss ja doch ein etwas größeres Tier gewesen sein bei einem Durchmesser des Kotballens von mindestens 2,7 Zentimeter.

Nochmals besten Dank und viele Grüße;

Volker

Hallo,

sicherlich kein Aptychus

Hallo Marc Philippe,

danke, ich dachte zunächst an einen Oberkiefer (Ryncholithes) oder Unterkiefer (Conchorhynchus) eines Nautiloideen!? Zum Vergleich lagen mir Kiefer-Abbildungen des rezenten Nautilus vor. An einen Koprolithen habe ich zunächst gar nicht gedacht, überzeugt mich aber momentan am ehesten.

Gruss Volker

Hi, Volker,

the visible morphology does not support the suggestion of a coprolite well. The "drying lines" or dents would not be expected in a coprolite. Drying dents require at least a coating such as a cuticula or soft shell, under which the drying would occur, or it could be a soft carapace that shows folding. If it were a coprolite, drying or concentration of the mass would appear more or less uniform. The surface would be more or less uniform granular, unless some undigested bodily ingestations are within.

Also, the punctiform indentations do not fit to a coprolite. Certainly, it is difficult to ascertain. To me, a possible explanation is a crustacean shell, e.g. an ostracode shell or that of a bivalved crustacean. It may have been shortly after moulting, thus still flexible and soft.

Hi Sven,

thank you very much! Yes, the surface of the fossil looks like a big "contact lense" => konvex, smooth, homogeneously. And, the ends of the "fold lines" are all showing to one area, the highest part of the object!

I also looked at the other side of the limestone plate (thickness: ~ 7 millimeter). There, the limestone shows a concave surface (negativ form). I think, if the object would be a coprolite, the surface on this side of the limestone has to be convex (I know that from coprolite findings in the oil slate of the Messel formation)!? So perhaps, your and Hans-Volker's explanation (crustacean shell) are not so far away from the truth :-)

All the best,

Volker   

Info!

above, you can see 2 additional photographs of the fossil object (lateral view and the other side of the limestone plate)!

To me, most likely an ostracode valve with diagenetic crushing scars and structure.

Thank you Bruno!

If it is centimetric I don't think it is a ostrocode. Ostracodes are mostly microscopical.

Agree with Ruben - this cannot be an ostracode.  I agree with you that the shape is somewhat like a natuiloid/amminoid but the patterns do not seem correct.  Perhaps due to preservation?  It reminds me somewhat of seeds that I see washing up on modern beaches.  In the US they are called "sea beans" by people who collect things on beaches.  Here's a link to some images . . .

http://tpwd.texas.gov/publications/nonpwdpubs/young_naturalist/plants/sea_beans/

Lynn

Hello Rubén, G. Lynn and all other followers,

thank you very much for your interesting infos! Now, we have collected several possible explanations:

- fragment of a cephalopod (?nautiloid) jaw;

- crustacean shell (most likely a big ostracode);

- coprolite (of an unknown, ?marin animal);

- seed (of an unknown plant, like "sea beans" on modern beaches in the USA).

I'm very pry, if we or somebody else can solve these "Gordian knot"  ;-)

Volker

Hello again,

here is a drawing (Ziegler, B. 1983: page 246, fig. 273) with the jaws (rhyncholithes and conchorhynchus; LxB: ~ 4 x 3 centimeter) of the modern Nautilus (Nautiloidea). You see, the shape and the size of my fossil object (which is perhaps only one half or a fragment of a jaw) is not so different with these cephalopod elements!

What do you think about this possible explanation?

And Phyllocarida?

Ok Javier,

thanks, maybe another posibility! Do you know something about the size range of fossil species of Phyllocarida? 

It is not my specialty, but Lower Cambrian Canadaspis was until 5.2 cm. and recent Nebaliopsis typica is nearly 4 cm.

Cheers

Javier, thank you for these informations!

What about Entomostraceans?

Ok Bruno,

i will check your information - thanks!

Dear Dr. Volker J. Sach,

I think your specimen may be a big otolith. Forms of otolithes are different, but your sample is like to some of these. For example see this article (sorry, in Russian, but there are a lot of such literature).

Good luck in your investigations.

Tetiana Stefanska

this is not fossils ..............

It looks like concretion. Is it possible to make up transverse section of the object?

Dear Tetiana, Saleh Lazam & Andrey,

thank you very much for your different ideas! I will try to check them as soon as possible ;-)

Best wishes;

Volker

Volker:

Solnhofen Plattenkalk are well eastablished to have been deposited in Lagoonal setting. In such an environment it is difficult to imagine any animal or even coprolite of this morphology. If you could just slice the margin of this object to observe the interior of visible "suture", which to me appears to be a possible concretionary structure. Do you find more than one such specimen showing similar feature?

Mit herzlichem Glueckwunsch !

Syed