Ioannis:

The image gives impression of being a high energy induced Pebbly Sandstone. Looks like a pseudofossil. Provide details of associated fossils if any, for further evaluation.

Best

Syed

in my opinion this could be a echinite.....

best regards

In my opinion this is Clypeaster sp.

Best regards

Dear Andreas Rohatsch and Diego A. García-Ramos you seem to be right! Clypeaster fits as a possible determination, although, late-Eocene deposits are indicating the development of a deep foreland turning the Eocene carbonates gradually into turbidites through a fine-grained transitional zone of marly limes to marls and shales. The fossiliferous interval may be part of the "pre-transitional" strata.

Thank you very much

Ioannis A.

Dear Ioannis,

you are very welcome. I am not an echinoid specialist but this cross-section of the test strongly reminds me of those of Clypeaster I have seen in Miocene and Pliocene outcrops. I read that clypeasteroids evolved in the late Paleocene - early Eocene from the cassiduloids (see e.g., Mancosu and Nebelsick, 2015). Therefore, your specimen may well be a clypeasteroid. They live from the littoral zone down to 500 m but they are fundamentally frequent in shallow water environments (Mancosu and Nebelsick, 2015). And the above statement is also my experience.

Best regards,

Diego

Clypeaster!

Klug:

Unmoeglich ! How do we expect calcareous test of Clypeaster to survive dissolution for so long in highly porous pebbly Sandstone? The key lies in detecting associated fossils.

Best

Syed

Dear all,

if Ioannis took the sample or he comes across it again in the field, he can pour some acid on it and check if it is carbonate.

Cheers

Diego

Diego:

The specimen you just posted is definitely an Echinoid, no need to test calcareous nature by acid treatment. However, specimen posted by Ioannis does not match your fossil. Let Ioannis find any other skeletal remains in highly porous pebbly Sandstone, which may be extremely difficult to find and may have been leached away.

Best

Syed

Dear Syed,

The rock which hosts the fossil (and not the pseudofossil) is not highly porous pebbly sandstone, but a (pebbly) microbreccious limestone with low porosity as a result of the calcareous matrix. I also didn't ask for the complete fauna assemblage, neither for the age, just an identification if it's possible of the fossil by this section.

Thank you very much for your time.

Ioannis A.

Ioannis:

First of all it does not look like pebbly microbreccious Limestone - associated skeletal elements were asked to possibly identify your specimen, which hopefully is not solitary one. In the absence of such an information, no one could ever identify your specimenn with confidence.

Best

Syed

Definatelly a clypeasteroid echinoid. Well preserved and not at all dissolved cross-section of Clypeaster test.

Rok:

You must be having some extraordinary insight to make this assertion based on just viewing the photograph. Ioannis who is having first hand information and access to field, must know that in support of your assertion the 'fossil' should stand the test of acid treatment for carbonate test and more importantly, should be able to encounter several complete or broken skeletal specimens. Your evidence is not straightforward.

Best

Syed

Dear Syed Abbas Jafar,

echinites, such as Clypeaster sp. are very common even in terrigenous influenced or dominated sedimentary rocks; e.g. in the Miocene (Serravallian) strata of the western rim of the Vienna Basin (Austria); a test with hydrochloric acid is not really necessary because the rhomboedric cleavage of the calcite is very good visible even in the presented picture....

The solubility of calcite depends, as you know of course, on different frame conditions, for example trace elements (e.g. Mg in the calcite of echinoderms) and the chemical composition of the pore fluid....

best regards AR

Andreas:

Thanks for your lucid response. However, I may emphasize that the only thing which seems to influence our esteemed respondents is the sectional outline of the specimen posted by Ioannis, resembling Clypeaster, but it does not match excellent and genuine specimen posted by Diego. A close look at the specimen of Iaonnis would reveal that there is not a single grain displaying rhombohedral outline suggestive of a carbonate mineral on the outline of the specimen. But yes, there are a few large scattered carbonate grains including one seen in the center of the specimen showing rhombohedral outline, which does not say anything.

Till concrete evidence is forthcoming I am inclined not to accept this as genuine clypeasterid fossil.

Vielen Dank und herzlichem Gruss..

Best

Syed

Dear all,

Just for curiosity and the sake of further comparison, I post another photo of a Clypeaster in coarse-grained sandstone. Note how the infilling sediment is finer-grained than the sediment surrounding the specimen. In general, the same seems to be the case with Ioannis' sample.

Another observation: the three samples posted here display internal pillars typical of clypeasteroids. See, for example: Grun et al. (2018)The taphonomy of Clypeaster: a paleontological tool to identify stable structures in natural shell systems. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 289(2), 189-202.

Cheers

Diego

Diego:

The picture of a specimen posted by you without an iota of doubt belongs to Clypeaster, mainly by the distinct presence of internal butteresses, also somewhat faintly observable in specimen of Ioannis. Secondly, your specimen shows appreciable thickness of wall with distinct rhombohedral outline. And finally the lower part of your specimen partly shows a 5-fold petaloid element with distinct row of pores.

With your further comments, we can only suggest affinity of specimen posted by Ioannis to Clypeaster, with typical diagnostic features still obscured.

Thanks and Best wishes.

Syed

Dear Syed Abbas Jafar,

you are right, that the first echinite is obviously not a Clypeaster but for shure a other echinite (maybe Scutella ?...- but I´m not a specialist on echinoids).......

and additional to my former answer I have to say that the marine Miocene sedimentary rocks of the Vienna Basin spans the Lhangian and parts of the Serravallian stages (regional stage Badenian)........

best regards

AR

Well, I think it might be a juvenile judging by the pen as a scale. Juveniles are more depressed than adults. Obviously the specimens I posted here are different taxa (C. cf. aegyptiacus (Zanclean), and C. gr. altus (Late Tortonian)) compared with the greek sample.

Following the nomenclature by Rose and Poddubiuk (1987), the morphology of the greek sample reminds me of the "biarritzensis" species group. But this is all in the realm of speculation because neither am I a specialist on echinoids. Plus I think the taxonomy of Clypeaster is still unresolved, pending revisions.

Best regards,

Diego

The internal pilars as buttress, clearly visible there, are a key for Clypaster identification. The cross section of the peristome is also unequivocal

Cheers.

I am agree with Rok Gašparič , the fosiil is from echinodermata phylum, and possible is clypaster and quartzifer coglomerate surround it.