Tuesday, September 1, 2009

Gastropod fossils from the Hauptrogenstein

Reactions:  
In my previous post I promised Aydin to post a few fotos of gastropod fossils that I came across during my mapping project. So follow-up on my promise here are four examples of fossil snails that one may come across in the oolithic Hauptrogenstein. My palaeontology isn't so great, and this was a mapping aimed at lime production, so we didn't bother so much about what these are exactly. If you can share some clues, feel free to contribute.


Sample from the Mumienbank, the top bed of the Middle Hauptrogenstein.
Oncoid with a gastropod nucleus. Probably a nerinea.



Detail from a polished slap of the Middle Hauptrogenstein. Somewhere from the "cross-stratified, oolithic complex" or coral-bearing Hauptrogenstein. Shells are 3 to 4 mm in size. Unidentified.


Gastropod sample from the coral-bearing Hauptrogenstein in close association with abundant coral debris (not recognisable in foto). A nerinean?


Wonderful 3D preservation of an archaeogastropoda(?) in close association with well-preserved, probably in-situ occurence, of branching corals (see below).


Branching-coral associated with the above mentioned gastropod fossil. Possibly encrusted with coraline algae?

3 comments :

AYDIN Ă–RSTAN said...

Cool! I especially like the 3D fossil shell. The things in the 2nd photo do look like snail shells, but not being a geologist or a paleontologist, I can't rule out anything else.

Anonymous said...

Nice photos--nice fossils!

In your second photo, the fossil at the bottom is a foraminifer, which you can distinguish by the arrangement of the chambers. The chambers start out in a "biserial" arrangement, not seen in gastropods (which of course have only one chamber), then become "uniserial". There are several genera that show this arrangement, but most are more recent than Jurassic; one possibility is Bigenerina, which ranges from Jurassic to Recent. The other two fossils in the same photo are probably small gastropods, though the one on the right could be a uniserial foraminifer, something along the lines of Dentalina, which is also the right age.

Cheers,
--Howard

Lost Geologist said...

Thanks Howard! That's some great clues you could share. I actually agree on the bottom one. I already thought it looks too odd for a snail with that un-snail-like chamber arrangment.