Mystery from the Black Cows – marine reptile expert needed

[Suchomimus]

G'day everyone,

maybe someone can help me with the identification of a fossil. Recently I was on vacation in France and had the opportunity to visit the famous Falaises des Vaches Noires at Villers-sur-Mer (Calvados, Normandy). While searching the beach at low tide I found many fossils of invertebrates, but at the end of it a loose bone, too, on the foreshore. So it is most likely from the Marnes de Dives formation (Callovian), but I cannot say for sure, of course (the Marnes de Villers is overlying).

As far as I know vertebrate fossils from there are represented by marine reptiles and dinosaurs (rare). My first thought was dinosaur, so I contacted Troodon. He does not think it is dinosaurian and recommended to post my find here.

My second thought was paddle bone from a marine reptile and from what I have seen it appears to be a possibility, but I am actually a dino tooth collector and would like to rely on opinions of people who are more familiar with bones than I am, especially with bones from marine reptiles.

 

Here it is (third picture: measured in centimeters):

 

 

Does anyone have an idea?

[pachy-pleuro-whatnot-odon]

With its shape being so round and stretched like that, marine crocodile vertebra would be the only suggestion I can come up with. I don't see this fitting anywhere on an ichthyosaur, nor on a plesiosaur, for which the supposed bone would be too thick as a paddle bone. In contrast to most other marine reptiles, marine crocodiles have elongated vertebrae with hollow/concave ends, a condition known as amphicoelous. Your find has only one concave end, however...

 

And while I don't want to burst your bubble, I actually think this is not a piece of bone at all, more likely being a worn sponge. That is, I don't see a bone texture. You find these sponges a lot in certain stretches of the beach around Vaches Noires, especially towards Villers-sur-Mer. In still remember myself having brought back multiple of these pieces, the first time I visited. In actually wrote a report about my finds back then on the Dutch fossil forum, and hope to translate and repost it here before too long. I also intend to do the same for my most recent trip, providing plenty of examples of the material that is to be found there...

 

What do you make of this, @taj?

[Suchomimus]

On 9/25/2021 at 1:50 AM, pachy-pleuro-whatnot-odon said:

With its shape being so round and stretched like that, marine crocodile vertebra would be the only suggestion I can come up with. I don't see this fitting anywhere on an ichthyosaur, nor on a plesiosaur, for which the supposed bone would be too thick as a paddle bone. In contrast to most other marine reptiles, marine crocodiles have elongated vertebrae with hollow/concave ends, a condition known as amphicoelous. Your find has only one concave end, however...

 

And while I don't want to burst your bubble, I actually think this is not a piece of bone at all, more likely being a worn sponge. That is, I don't see a bone texture. You find these sponges a lot in certain stretches of the beach around Vaches Noires, especially towards Villers-sur-Mer. In still remember myself having brought back multiple of these pieces, the first time I visited. In actually wrote a report about my finds back then on the Dutch fossil forum, and hope to translate and repost it here before too long. I also intend to do the same for my most recent trip, providing plenty of examples of the material that is to be found there...

 

What do you make of this, @taj?

 

Thanks for your reply, a fossilized sponge was a possibility I did not really think about. After reading your post I did some research and indeed – I found some examples of sponges from Villers-sur-Mer that are pretty good matches considering that my find is worn.

 

No bubble bursted, I am glad to know now what it is. And I would definitely like to read your report!

[taj]

Unfortunately , I would agree with you , Pachy . That is one of the traps of the site ,all these bits of rocks that get weathered and ground up until they look like some fossil bits ...