Hi Zbyszek,

Your "microproblematica" look like invertebrate coprolites ... sometimes described as "Coprolus spp." ... Please compare e.g. Vangerow, E.F. (1953): Koprolithen aus der Aachener Kreide. Senckenbergiana 34 (1/3): 95-98; Frankfurt/M. or Amerom, H.W.J. van (1971): Kotpillen aus der Oberen Kreide im Maastricht-Aachener Raum (Nord-West Europa). Mededelingen Rijks Geologische Dienst (N.S.) 22: 9-19; Maastricht.

These coprolites are often common in Maastrichtian chalk deposits of Europe ... Best wishes, Mike

Dear Mike,

I will be also  interested in pdf of those papers, if you have them of course.

best, Zbyszek

These are isolated coprolites. To get some more precision on their taxonomic assignment, you should cut some transverse thin sections (for review, see the internet site of Joachim Blau: www.staff.uni-giessen.de/~gg13/FAVRIS/DECAPODA/FAVREINA/FV___OPT.HTM).

If these remains are hollow structures with a shiny proteinaceous wall (as they appear to be) then they are not likely to be coprolites. There are a host of arthropod eggs/pupae that take this shape and are of this size with a chitin-like wall and various polar plugs and extensions. See e.g. robberfly eggs at http://www.arkive.org/hornet-robberfly/asilus-crabroniformis/image-A2432.html or some more extravagantly ornamented examples of terrestrial arthropod eggs at http://www.micronaut.ch/product-category/insect-egg-sem/    You would need to look at the wall structure with high-power light microscopy or SEM to confidently assign them to a group. If the wall is a 2-layered structure consisting of irregular interwoven layers of secreted threads then they may even be clitellate annelid cocoons, e.g. Manum, S.B., Bose, M.N., & Sawyer, R.T., 1991: Clitellate cocoons in freshwater deposits since the Triassic. Zoologica Scripta 20, 347-366..

Dear All, thanks for your suggestions.

I have looked inside these "things" under SEM and they are not hollow structures. In fact they are mineralized (phosphatized) and composed of apatite. On the cross section they are structureless - maybe due to phosphatization. So at this moment I can not say they are surely "microcoprolites" or anything else...?

Dear Stephen, did you see the phosphatized eggs/pupae or cocoons? It could be interesting to compare.

best, Zbyszek

Dear Diego and Zbyszek,

I'm moving momentarily from Göttingen to Munich ... starting a new job next Wednesday, so unfortunately all papers and books are already packed ... please remind me late October ([email protected]) to send you pdfs of these papers ...

Best wishes, Mike

Most likely are arthropod eggs.

The more I think about it, the more closer I'm the statement that they are microcoprolites. It is also well in line with the fact, that they are phosphatized, since the fecal pellets can simply induce this process.

Mike, thanks for the requested pdf.

best, Zbyszek

Very similar structures occur in large numbers in e.g. the Lichtenberg Horizon of the ENCi quarry. These were described by Van Ameron 1973 as Coprolus maestrichtiensis, 

Kenneth, thank you for the paper. Most probably [now, I'm almost sure] that these "things" are microcoprolites.

Unfortunately, I can not fulfill your request and provide your regards to Prof Adam Urbanek - he passed away this summer...

Dear Everybody,

I think that "microproblematicum" is no more "problematicum". I think that microcoprolites fulfill this topic, however I'm still openminded:). Therefore, thank you for your contribution in this question.

Zbyszek

Stijn is correct in saying that they are known from ENCI as I have found them in samples. They are also in many residues of Cretaceous chalks in the UK. I have always regarded them as micro-coprolites because of shape and composition. I did thin-section some 40 years ago, but found nothing diagnostic inside. Worth trying again!