Show Your Rudists!

[Quer]

32 minutes ago, DPS Ammonite said:

t may have a strange form for a rudist, but it looks much closer to bivalve clam in form than most rudists.

You are right. I think I've been so used to hippurites or radiolites with strongly unequal valves that it may have escaped me.

[Quer]

Another local rudist species used as stratigraphy marker for upper Campanian in South-central and South-eastern Pyrenees: Radiolitella pulchellus (Vidal, 1878).

 

Recently I have found this small specimen with its left -or upper valve- notable well preserved:

 

 

 

First described and figured by Vidal as Sphaerulites pulchellus, reclassified by toucas as Praeradiolites pulchellus and reclassified again by J.M.Pons as Radiolitella pulchellus.

 

 

More about taxa first described by Catalan paleontologist Luis Mariano Vidal here (pp.55-56 for this species) and the use of rudists as stratigraphy markers in South Pyrenees here

 

 

 

 

[Tidgy's Dad]

On 1/3/2020 at 5:25 PM, Quer said:

Another local rudist species used as stratigraphy marker for upper Campanian in South-central and South-eastern Pyrenees: Radiolitella pulchellus (Vidal, 1878)

 

 

 

 

That's beautiful.

[Quer]

Biradiolites royanus (d'Orbigny, 1850) is another small and very characteristic radiolitid, often side by side with R.pulchellus in Late Campanian layers of SE Pyrenees. The costae produced by RV folds at the outer shell surface -specially the central one- made it a distinctive beaker-like shape.

 

 

 

 

D'Orbigny described it in 1850 on the basis of specimens from Charente-Maritime, France. Vidal created a different species  in 1878 and called it Agria fumanyae. Finally, rudist expert E.Vicens synonimized them in 1992.

 

 

As far I know, found only in Aquitaine (Cherente-Maritime, Charente, Dordogne) and South-central Pyrenees.

[Quer]

Not far from I live (SE of Pyrenees) there are a mountain stream which carved its bed through many rudist formations, some of them measuring tens of meters long and several meters thick.

Though erosion and crystallization make ID difficult, some of those formations look spectacular. Unfortunately, it is not an easy access place, as it is necessary to wait the torrent being absolutely dry, meaning a dry summer.

Main components of this formations are, likely, Hippurites lamarcki (Douvillé, 1895) or/and Hippurites vidali (Matheron, 1880). Those are local stratigraphy markers for middle and lower Campanian, respectively.

I hope you enjoy.

 

A more close-up view

 

 

Another ticket, and in this one all individuals are upwards and equally oriented. Sometimes this is known as "living position":

 

 

A bigger formation:

 

 

Some details:

Vertically sliced specimens, showing the successive chambers the living organism habited as the shell grew, separated by layers called tabulae.

 

 

 

Shells can reach 80 cm high:

 

 

Interior of shells can be very -and beautyfully- crystalized

 

[FranzBernhard]

Very, very instructive and very, very beautiful! Thanks for sharing!

@Tidgy's Dad, @Monica

Franz Bernhard

[Quer]

I labeled this one as "unidentifiable steinkern" some months ago, but recently I have discovered it is a Praeradiolites hoeninghausi (Des Moulins 1826). It seems to be more or less common in Aquitaine (Charente, Dordogne...), but rare South of Pyrenees (Upper Campanian)

 

 

Compare with this specimen from the Muséum National d'Histoire Naturelle (Paris)

 

Or with this one from https://www.steinkern.de/steinkern-de-galerie/sonstige-fundorte-oberkreide/praeradiolites-sp-14277.html

 

Upper and bottom views:

 

 

 

[Tidgy's Dad]

That's a particularly nice and interesting specimen.

Goodness, rudists were weird things.

[Quer]

Thank, Adam and all for you appreciation. Certainly, it is one of the weirdest.

 

What puzzles me most is this zone circled in red, present in all cases. It not seems to me the typical cellular rodiolitid structure, nor ornamentation.

 

 

 

 

[FranzBernhard]

2 hours ago, Quer said:

What puzzles me most is this zone circled in red, present in all cases

Maybe this has something to do with the myophores? Position would fit. Are they on both sides of the rudist?

Franz Bernhard

 

 

[Quer]

Yess...! I think you are right, Franz, anterior/posterior adductor scar on myophore. Not symmetrical, not so clear, but it could be something similar on the other side.

[herve]

Rudistes  From urgonien stage Orgon France. 2 réquiénia ammonia and one toucasia carinata

[herve]

Two réquiénia ammonia

[herve]

Toucasia carinata

[Quer]

Recently have been published in open access this most interesting article about an Hippurites radiosus-based reef in my area (SE of the Pyrenees, upper Campanian strata).

This paper contains information and pictures far beyond my knowledge and capabilities, but I think I can add some close-up pics I take some months ago.

 

Spanish specialist Enric Vicens said that "All the specimens of Hippurites radiosus des Moulins have a very characteristic ornamentation: the ribs, 5 per centimetre, are fine, rounded and separated by a narrow groove. There are small rounded spines in the intersection between these and the growth lines."

 

And so it is:

 

 

 

 

"The pores of the left valve are linear or vermiculate and vary in length":

 

 

"The "arête cardinale" is triangular, and its end may be prologed as a lamina. (...) The first pillar is smaller than the second although it is generally more robust":

 

[Quer]

A notable characteristic of this reef, partially composed of specimens in life position, is its important endo-epibiont colonization.

 

Abundant colonizers are ostreids (Probably Amphidonte pyrenaicum):

 

 

 

Which, in turn, are colonized by other bivalves, briozoans, serpulid worms...

 

 

 

 

And obviously, corals are part of the reef construction:

 

[Quer]

Hi,

Some weeks ago, I learned about a forest track opened one to two years ago in a potentially fossiliferous zone not far from I live.

 

To give you an idea of it, here it is a view:

 

 

It turned to be an interesting, untouched site containing rudists, corals, ostreids and, to a lesser extent, some pectinids and echinoids.

 

Edit: I forget to say the strata is Upper Campanian, and location SE Pyrenees.

 

Concerning rudists, one of the principal genera is Hippuritella sp.:

 

 

 

This last pic taken with the help of my nephew

 

Probably, they are the Hippuritella nov. sp. 1 described by rudist specialist E.Vicens (figures 11-14 from the paper: https://www.dst.uniroma1.it/Volumi/VOL 28/GR_28_119_161_Vicens.pdf

 

 

Upper valves are often preserved, and I've picked and prepared a couple of specimens:

 

 

 

(In this pics the channel-pores structure are clearly visible)

 

 

Edited 6 hours ago by Quer

[Quer]

Another species not rare in my area, of which I've not talked about, is Praeradiolites boucheroni, a big radiolitid:

 

 

 

This is a species not easy to ID, except if it is broken in a fortunate way, and you can compare it with this figure: (from https://www.ucm.es/data/cont/media/www/pag-33428/Rudist Biostratigraphy.pdf)

 

[rocket]

I add some rare rudists from northern germany

first one comes from upper turonian of Dortmund

 

[rocket]

lower upper turonian from Stadtlohn near Ahaus, NW-Muensterland basin

 

[rocket]

another incredible rare find, not mine, its in the collection of a friend of mine

Ruhrgebiet-area