Some Rudists from the Campanian St. Bartholomä-formation, Gosau group, Eastern Alps (St. Bartholomä, Styria, Austria)

[Tidgy's Dad]

The hungry Lithophaga is very interesting.

[FranzBernhard]

Two somewhat "colorful" polished cross sections of Hippurites colliciatus, about 3 mm apart, intergrown with two rudist fragments. Position of teeth and one muscle is visible at the top of both sections.

 

Somewhat remarkable is the immense density of clionid borings in the rudist´s shells. The borings are filled with greenish and brownish sediment.

 

This is the only rudist specimen I have collected in St. Bartholomä, that has absolutely no infill of fossiliferous limestone or attached to it. Beside the clast in the lower right of the left specimen, the sediment is only of the younger, mostly greenish type, containing some very small quartz grains dispersed throughout. Judging from this and 1) clionid borings exclusively filled by younger sediment and 2) preservation of teeth and muscle positions, despite being filled with younger sediment, it could be concluded, that this rudist has grown just before it was catched by the debris flow, together with all the other clasts of fossiliferous limestone and rudists, that have grown a few milllion years earlier. Together, they are now components of the "Knödelbrekzie" (debrite). It´s just a hypothesis ... 

Franz Bernhard

[Tidgy's Dad]

Hungry clionids this time.

Reasonable hypothesis, I would say.

Nice specimen. 

[FranzBernhard]

Two cross sections, 3 mm apart, of Hippurites colliciatus (left) and a radiolitid rudist (Radiolites angeiodes?, right), grown together and firmly embedded in fossiliferous limestone. I did not recognize that there is also a radiolitid in this specimen until I had it cut in halve. The higher section of the radiolitid (at 3 mm) has the position of one of its teeth nicely preserved by different generations of sediment infill.

Franz Bernhard

[FranzBernhard]

Some rudist specimens are somewhat "fuzzy", as these polished vertical sections of this bi-valve radiolitid are. Somewhat colorful, but not really much to see. In the right section, there seems to be a Lithophaga sp. in the upper part.

Franz Bernhard

[FranzBernhard]

No new rudist today, just links to my albums, where I have uploaded all my polished hippuritid rudist transverse sections from St. Bartholomä, Styria, Austria:

 

http://www.thefossilforum.com/index.php?/gallery/album/2912-vaccinites-vesiculosus-woodward-1855-from-st-bartholomä-styria-austria/

 

http://www.thefossilforum.com/index.php?/gallery/album/2913-vaccinites-alpinus-douvillé-1897-from-st-bartholomä-styria-austria/

 

http://www.thefossilforum.com/index.php?/gallery/album/2914-hippurites-nabresinensis-futterer-1893-from-st-bartholomä-styria-austria/

 

http://www.thefossilforum.com/index.php?/gallery/album/2918-hippurites-colliciatus-woodward-1855-from-st-bartholomä-styria-austria/

 

http://www.thefossilforum.com/index.php?/gallery/album/2919-hippurites-colliciatus-woodward-1855-pseudocolonies-from-st-bartholomä-styria-austria/

 

http://www.thefossilforum.com/index.php?/gallery/album/2920-hippurites-colliciatus-woodward-1855-with-radiolitid-rudists-from-st-bartholomä-styria-austria/

 

Franz Bernhard

[FranzBernhard]

This is my first attempt of a hippuritid vertical section. The polished sections are about 3 mm apart, the specimen has no left (upper) valve.

 

osl: outer shell layer.

isl: inner shell layer.

mc: main (body) cavity.

L: ligamentary pillar.

P1, P2: P1-, P2-pillar.

pm: posterior myophore

(pm): position of posterior myophore. No upper valve preserved, hence only sediment infill.

This is in contrast to AN3948, with actually preserved posterior myophore (sparry calcite surrounded by sediment, followed by sparry calcite of the myophore socket).

am: anterior myophore.

at: anterior tooth.

pt: posterior tooth.

(pt): position of posterior tooth. No upper valve preserved, hence only sediment infill. Some sparry calcite could be part of pt, but I am not convinced.

This is in contrast to AN3948, with actually preserved teeth (sparry calcite surrounded by sediment).

 

I have tried to indicate in two different transverse section the position of the vertical section:

AN3948 is a Vaccinites vesiculosus from St. Bartholomä, for a serial section of this specimen see:

http://www.thefossilforum.com/index.php?/gallery/image/49950-an3947_an3948/

Another serial section with myophore and teeth preserved is here:

http://www.thefossilforum.com/index.php?/gallery/image/50073-an4150_an4151_an4152/

Redlich, 1899 is an old drawing of a Vaccinites vesiculosus from Gosau-sediments of Carinthia, Austria.

 

I am far from sure, if everything is correct. Comments, corrections, suggestions are welcome!

 

Franz Bernhard

[Tidgy's Dad]

Have no idea if it's correct or not, but it is very, very interesting.

[FranzBernhard]

This is the yield of polished traverse sections of rudists of about 3 hours of digging and searching at 03/17/2019 at point 36 west of Kalchberg, St. Bartholomä, Styria, Austria.

Campanian St. Bartholomä-formation, Gosau-group, Eastern Alps.

AN4163, AN4164: Small pseudocolony of Hippurites colliciatus with good contrast. There are also shell fragments of larger rudists attached to it.

AN4161, AN4162: Hippurites colliciatus with rather poor contrast; teeth and posterior myophore are visible.

AN4167: Lower valve of radiolitid rudist with cellular outer shell, no ligamentary pillar visible.

AN4165, AN4166: Lower valve of radiolitid rudist with rather massive outer shell. Teeth (sparry calcite) and parts of teeth sockets are visible left and right of the ligamentary pillar. Myophores (sparry calcite left and right of the teeth) are also partly preserved. AN4166 is ca. 3 mm higher up the shell than AN4165.

Franz Bernhard

[FranzBernhard]

Another rudist from 03/17/2019 at point 36 west of Kalchberg, St. Bartholomä, Styria, Austria.

It´s a vertical section of a small (4 cm high) radiolitid. Its an empty halve-cone, the outside is intergrown with limestone (see polished left side). There seem to be small parts of the upper valve preserved. Interestingly, the lower valve is not cellular, but massiv-lamellar. Not many radiolitid genera have this type of shell, but I don´t know what. Anybody knows them ? Many thanks !
Franz Bernhard

 

[FranzBernhard]

The next radiolitid vertical section. Like the specimen before, its also an empty half-cone. Specimen is about 4 cm high and the polished part (right) has a very low contrast (pic is rather strongly contrast-enhanced). However, it shows quite nicely the alternation of cellular and massiv-lamellar outer shell layers of the lower valve. Somewhat nice are also the pronounced "wings", which I have not seen so clearly in material from St. Bartholomä until now.  A small part of the upper valve is also visible in the polished part.

Franz Bernhard

[FranzBernhard]

A slight twist to the theme of "empty halve cones" ...

This fragment of the lower valve of a radiolitid rudist is in its natural, strongly weathered state. The left part is a natural, near vertical section throuth the valve, showing the typical cellular outer shell, nicely highlighted by weathering. The ligamentary pillar is also there, but also strongly weathered. The out-of-focus, lower part of the rudist fragment is still filled with limestone. That´s all .

Franz Bernhard

[FranzBernhard]

My digging at point 36, west of Kalchberg, St. Bartholomä, Styria, Austria, at 07/30/2019 was not very successful. However, two fragments of radiolitid rudists were found, which could also be posted as "lovely couples" :

They show roughly the same part of a radiolitid rudist, but nearly completely different things, they are somewhat complementary:

The left one is a fragment of a lower and an upper valve, still attached to each other, with the ligamental pillar preserved in both fragments. Only outer shell is preseved in this specimen, no inner shell (as is mostly the case).

The right one is a partial steinkern of a lower valve near the commisure. The former ligamental ridge can be seen as a vertical groove in the middle of the specimen. To the right and left of the ligamental pillar are perhaps the fillings of the accessory cavities; further to the left and right are the fillings of the tooth sockets with very nicely preserved grooves on them.

 

For comparison, here are two radiolitids from the literature. First one is from Skelton (2013); the accessory cavities are just to the left and right of the ligamentary infolding. Second one is a drawing from Skelton (1979).

Franz Bernhard

[FranzBernhard]

This specimen is from a forest road I am walking regularly to reach my usual spots at Kalchberg-East (Point 25 and 38), St. Bartholomä. I have already found two hippuritid rudists in this road gravel two years ago. At 08/21/2019, I looked as usual at the (same) gravel, and this time, I spottet the next rudist. The upper valve was visible and it is a somewhat puck-shaped, heavily worn fragment of a radiolitid rudist.

 

Bonus: Both valves are there! So I was hoping, that teeth or myophores could be preserved. I made a transverse section through the lower valve of this ugly blob, cut about 1 cm below commisure. I was not disappointed! Despite being a rather poor-contrast specimen, it shows quite well both teeth (at, pt) and especially well both myophores (am, pm), both consisting of their original, although recrystallized material (former aragonite, now calcite). The ligamentary pillar is also there (L), it seems to be split in half(?). Not much is preserved of the inner shell layer of the lower valve, but some can be seen especially above the anterior tooth (at). Main (mc) and accessory cavity (ac) are filled with fossiliferous limestone, the outer shell has the typical cellular structure. For some explanatory pics from the literature see previous post.

Franz Bernhard

[FranzBernhard]

From time to time, simple, but somewhat strange objects turn up in the Campanian of St. Bartholomä. However, this item is not as strange as it might look at first sight. It seems to be a fragment of the P2-pillar of a large Vaccinites alpinus. The transition to the broken off, slender "steem" can be seen at the top left of the right pic and at the left edge of the middle pic. Tightly spaced growth lines are visible in the left and middle pic. It was found during digging in weathered "Knödelbrekzie" (clasts of fossiliferrous limestone in marl), no prepping involved, just cleaning.

 

For comparison, part of a transverse section of a V. alpinus with all three pillars:

Franz Bernhard

[fifbrindacier]

Beautiful specimen and photos, thanks to share it Franz.

[Tidgy's Dad]

Nice to catch up on this excellent and informative thread. 

 

[FranzBernhard]

Long time no post here...

I have polished this specimen from St. Bartholomä last Sunday, but have already collected it about a year ago.

It shows quite nicely the structure of the outer shell layer of the lower valve of radiolitid rudists in transverse (left) and longitudinal (right) section side by side. I think, the left one has grown on the right one, but I could be wrong.

Franz Bernhard

[FranzBernhard]

Will copy over some specimens from other threads:

For example, this large segment of the lower valve of a radiolitid rudist. Its the largest specimen of this kind I have found so far in St. Bartholomä:

Franz Bernhard