ondrej.zicha Posted June 4, 2015 Share Posted June 4, 2015 Hello everyone, these fossils are quite common in at least one Czech locality of Bohdalec formation (upper Caradoc/Beroun) and I wondered if anyone has seen anything similar somewhere. The fossils are lentil shaped, with a thin egg-like shell that could be cracked and removed to expose inner layer of different color and structure. The size is 1 to 4 mm in diameter. I've consulted some experts and although they've all encountered similar fossil, they have no idea what it is. One of the opinions was that it could be a juvenile cystoid of some sort, for example Echinosphaerites seems to be common in this formation, although never found on this locality. However no one seems to have done any research into this yet. Associated fauna are small cyclopygid and illaenid trilobites, small brachiopods, graptolites, bivalves and ostracods. Thanks in advance for your thoughts Ondrej Link to comment Share on other sites More sharing options...
abyssunder Posted June 4, 2015 Share Posted June 4, 2015 I think they are Ostracods(crustaceans) with their flattened bodies protected with chitinous/calcerous valves,with dimensions between 1and 4mm.But is just my guess. " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
JimB88 Posted June 4, 2015 Share Posted June 4, 2015 I concur..here's an interesting paper on the subject http://www.academia.edu/10351478/The_earliest_ostracods_from_the_Ordovician_of_the_Prague_Basin_Czech_Republic Link to comment Share on other sites More sharing options...
ondrej.zicha Posted June 4, 2015 Author Share Posted June 4, 2015 Thanks for the tip! This has never occurred to me, since I'm more familiar with standard bean shaped ostracods with altogether different preservation. Link to comment Share on other sites More sharing options...
FossilDAWG Posted June 4, 2015 Share Posted June 4, 2015 They do not look like ostracods to me. I don't see any evidence of a hinge, and none of them show evidence of having two "valves". Also, they look as if they were somewhat flexible; at least, they are flattened in a manner that preserved folds rather than cracks. Flattened ostracod shells look obviously crushed, with lots of cracks. Finally, the rim around the entire of the periphery is a feature I have not seen in ostracods; some have a rim around part of the carapace but not at the hinge region. They also do not look echinoderm to me, as there isn't obvious evidence of calcarious plates. Unfortunately I don't have a suggestion for what they may be. Don 1 Link to comment Share on other sites More sharing options...
MarcusFossils Posted June 4, 2015 Share Posted June 4, 2015 (edited) I'de agree with FossilDAWG, that they aren't ostracods. The original cystoid idea seems more likely. Out of my rather uninformed opinion, could it be that they are eggs or juvenile corals of some sort? Edited June 4, 2015 by MarcusFossils Website: https://www.instagram.com/paleo_archives/ --------------------------------------------------------------------------- “It is by no means an irrational fancy that, in a future existence, we shall look upon what we think our present existence, as a dream.” ― Edgar Allan Poe Link to comment Share on other sites More sharing options...
Carl Posted June 4, 2015 Share Posted June 4, 2015 I also don't see ostracods here. They seem too circular to be ostracods. Link to comment Share on other sites More sharing options...
ondrej.zicha Posted June 4, 2015 Author Share Posted June 4, 2015 I was able to google some round-ish ostracod species and I thought the valves might be sort of fused together during fossilisation, but I'm not convinced either way. I have some juvenile cystoid fossil (not of Echinosphaerites though) of comparable size in my collection, but stem base is clearly visible, it is nowhere near circular as that. The corals are unlikely as the Ordovician sea of Czech Republic was a cold one, I have heard of no fossil corals until Silurian. They could be some algae though. Eggs are not likely either I think, because the fossils come in different sizes. Eggs of some sort - if they were even preserved - would likely be uniform size. Link to comment Share on other sites More sharing options...
Diceros Posted June 4, 2015 Share Posted June 4, 2015 I agree with the majority that they aren't ostracods. In addition to the good reasons cited by FossilDAWG, they also appear to have an inner, slightly spiky organic layer - like they were trying desperately to avoid drying out (sadly, they failed). I think they were originally disc-shaped, and only flattened to the lenticular shape. I also think echinoderm is unlikely, as there's no evidence of calcite plates. I think some sort of elaborate cyst is a possibility. Link to comment Share on other sites More sharing options...
FossilDAWG Posted June 4, 2015 Share Posted June 4, 2015 Could they be opercula of something? Not gastropods, the shape is too circular, but something else. Are there any tube-shaped organisms with a round cross section associated with these fossils? Don Link to comment Share on other sites More sharing options...
ondrej.zicha Posted June 4, 2015 Author Share Posted June 4, 2015 Not likely, there are rare hyolithids, but this doesn't look like hyolithid operculum. Only other fauna I've found was both articulate and linguliform brachiopods, cyclopygid and illaenid trilobites (indicating deeper environment), bivalves, graptolites, regular small ostracods and possibly fragments of conularids, although I'm not much sure about those, everything in quite minute specimens, also indicating deeper sea with scarce oxygen. No gastropods were found so far, nor cephalopods, echinoderms or bryozoans. Link to comment Share on other sites More sharing options...
Acryzona Posted June 5, 2015 Share Posted June 5, 2015 They're very intriguing. I'll throw my hat into the non-ostracod camp. Could it be some dermal plate? Collecting Microfossils - a hobby concerning much about many of the little paraphrased from Dr. Robert Kesling's book Link to comment Share on other sites More sharing options...
piranha Posted June 5, 2015 Share Posted June 5, 2015 Someone suggested to me a resemblance to a possible cyclocystoid. One of the posted examples appears to have similar characteristics: This monograph reports a range of Lower Ordovician (Llanvirnian) to Upper Devonian (Frasnian) for cyclocystoids in the Czech Republic. Smith, A.B., & Paul, C.R.C. (1982) Revision of the class Cyclocystoidea (Echinodermata). Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 296:577-679 Link to comment Share on other sites More sharing options...
Rockwood Posted June 5, 2015 Share Posted June 5, 2015 Perhaps the dormant stage of something similar to a bryozoan hibernacula or statoblast ? 1 Link to comment Share on other sites More sharing options...
ondrej.zicha Posted June 5, 2015 Author Share Posted June 5, 2015 Perhaps the dormant stage of something similar to a bryozoan hibernacula or statoblast ? This is an interesting opinion, although I'm not sure why would sea bryozoans evolve such mechanism of survival - statoblasts are present in freshwater bryozoans, where there is possibility of drying of habitat or need to colonize new water body by being transported by animals. This was a deep water environment, possibly with lack of oxygen and solid surfaces to grow on. These could be the factors to influence evolution of bryozoans (or possibly other animals) to form such dormant stages and hope for ocean currents to move them into some more acceptable environment. I'm no expert on deep sea currents but I'd expect their chances of being transported to a better place would be quite slim. It's definitely worth looking into though. Link to comment Share on other sites More sharing options...
ondrej.zicha Posted June 5, 2015 Author Share Posted June 5, 2015 As for the cyclocystoids, I actually have no information about this group present in Czech Ordovician and I can't access the referenced book. Is there some particular species mentioned? However although there is some resemblance, there are really no signs of sutures or plates or anything indicating these are echinoderms, at least not adult ones. Besides, the rim is irregular, however showing some signs of a bilateral symmetry in some specimens. Link to comment Share on other sites More sharing options...
Shamalama Posted June 5, 2015 Share Posted June 5, 2015 Just throwing this out there but could it be some kind of foram or other plankton? -Dave __________________________________________________ Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPheeIf I'm going to drive safely, I can't do geology. - John McPheeCheck out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/ Link to comment Share on other sites More sharing options...
Auspex Posted June 5, 2015 Share Posted June 5, 2015 This seems echinoderm-like, as in exfoliated cystoid: "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Diceros Posted June 5, 2015 Share Posted June 5, 2015 Really good puzzler, ondrej.zicha! Thanks for the fascinating post. Most posts aren't anywhere as complex as this one. Obscure morphology, obscure time period, obscure habitat - what more could one ask? Your excellent photos help keep it on track. Link to comment Share on other sites More sharing options...
FossilDAWG Posted June 5, 2015 Share Posted June 5, 2015 Just to be clear, is the inner surface (after removal of the egg-shell like layer) another layer of a different material with short spines, or is it a mold of the inner surface of the egg-shell like layer? If it is the latter, the spines could be molds of pores in the egg-shell like material. Don Link to comment Share on other sites More sharing options...
ondrej.zicha Posted June 5, 2015 Author Share Posted June 5, 2015 Just to be clear, is the inner surface (after removal of the egg-shell like layer) another layer of a different material with short spines, or is it a mold of the inner surface of the egg-shell like layer? If it is the latter, the spines could be molds of pores in the egg-shell like material. Don So I dissected one, although I wanted to save these for the experts, the locality was unfortunately only temporary and I'm not sure I'll be able to find any more any time soon. Alas, maybe experts here will do the job just as fine (or better). As for the question, seems to be the latter case, although the material looks different than the matrix stone, but this can be because of some chemical processes inside the shell, or vice versa. Here are more photos of one of the specimens. Also notice that the pores seem to be more dense on one side. Link to comment Share on other sites More sharing options...
ondrej.zicha Posted March 23, 2019 Author Share Posted March 23, 2019 Hello again, here's an update for those that are still interested: I was able to find a report of possible foraminiferans and Czech Ordovician. I've contacted the author and he thinks that these are the similar fossils he has obtained while dissolving shales. According to him, the fossil is possibly genus Thurammina or Cribrosphaeroides, although there are other similar genera. Meanwhile I was able to find different specimens in different formations of Czech Ordovician, see photos - most of them are Dobrotiv formation (Middle Ordovician) found in nodules, last three photos are Upper Ordovician Králodvor formation. Some might be only oolites (or at least were considered oolites by other paleontologists), but they all seem to have sort of shell around them (however this one does not seem porous as in other specimens). Opinion however differs if these are really foraminiferans. Several other fossils earlier placed in this group are now believed to be more likely cysts of some protist algae. It certainly needs more research, however there's currently no one interested in studying these fossils, even though they seem to be important faunal element of at least Czech middle to upper Ordovician (with other similar "foraminiferan" genera present in Cambrian and also Silurian and Devonian). 4 Link to comment Share on other sites More sharing options...
Rockwood Posted March 23, 2019 Share Posted March 23, 2019 Thanks for the update. Hope it attracts need attention to the subject. Link to comment Share on other sites More sharing options...
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