Two Fossils From Czech Llandovery Formation

[ondrej.zicha]

Hello again,

here are another two fossils (or not) that I'm unable to place. They come from llandovery formation locality Hýskov from a shallow sea rich with trilobites, graptolites, brachiopods, bryozoans and crinoids. All other llandovery formation localities in Czech republic are deep sea shales with only graptolite fauna and very few brachiopod species.

1) Hýskov is very rich with beautiful graptolite fauna, like this dendroid Dictyonema graptolites. This fossil (if it is fossil) is preserved in a very much same way as the graptolites, while other fauna there is more plastic.

2) This one is probably a cephalopod of some sort, probably related to Cyrtoceras? However I can't see any segmentation. The white structures are probably only some sort of secondary minerals?

Thanks in advance for your opinions

Ondrej

[Plax]

#1 looks like a pelecypod

[dshamilla]

Ondrej,

For Fossil #1, the mode of preservation suggests chitin and in all probability is a part of an arthropod; what kind I don’t know. Fossil #2 is most likely as you pointed out a Cyrtoceroid cephalopod. The infilling of your specimen is reminiscent of cone-in-cone, and it may be cameral deposits (some are bizarre). Some of the lower Paleozoic cephalopods, instead of developing enlarged siphuncles to act as ballast, would make chemical deposits in the apical area of the phragmacone on the inner sides of the camera, where the septum meets the shell wall. Because of the lack of any other truly cephalopod characteristics, I thought I would point out the following: dependent on the original orientation of your specimen, there is a proported Llandovery age “burrow” cited in an old reference as Histeoderma hibericum in which the lower portion of the burrow bears a striking resemblance to your specimen. I tried to follow up on the binomen but wasn’t able to find anything. It may not even be considered a burrow anymore. The reference is Baily W.H. 1875. Figures of Characteristic British Fossils with Descriptive Remarks, Volume 1, Palaeozoic. Van Voorst, London and is available for download at numerous Internet sites. The curvature of the “burrow” is almost exactly the same but I could not find a reference scale. Just throwing this out there as an alternative possibility.

[Avalonian]

I'm sure you've identified these by now but...

2) I have a fossil with similar preservation from the Llandovery in England and I'm reasonably sure it's a coral. The very small outcrop has produced a number of corals, varying in size / shape / preservation, along with many brachiopods and at least one bryozoan with unusually detailed preservation for that location. I'd post a photo but my camera isn't good enough, sorry.

[Avalonian]

I did manage to get a photo, although it's not ideal. 3x3cm. Reasonably sure mine is a coral.

 

(Posting again. Apologies to the mods if this duplicate comment looks odd.)