Bite mark??

[CWS]

Picked this up in Dorset, I've only cleaned in fresh water and that hole appeared in the keel of the Nautilus. Its very well defined, what do you think, possible tooth damage? Appreciate your thoughts.

 

 

[Troodon]

Can you take a photo of that hole without a shadow.  Does not look very deep for a bite mark.

[CWS]

Sure, it looks like it went diagonally as it's broken the shell above. Hard to say how deep it is as was full of sediment but it's about 15mm with what I cleaned out, if that helps.

[Troodon]

Thank you.  I don't see a bite the inside is pretty rough.

[CWS]

Wouldn't the shell have been hollow when it was alive/ bitten, and then filled with sediment as it lay on the bottom and fossilised?

[Troodon]

Hey anything is possible but the ones Ive seen bitten have round holes not rectangular.   Just seems like natural erosion and no regrowth around the perimeter of depression.  Let see what others say, predation is not an easy call.

[JohnJ]

Holes like this can often be the result of a fully 'decayed' marcasite (or some other iron based mineral) nodule.  The dark brown remnants look like they are visible in the large hole and as small inclusions in other spots.

[CWS]

17 minutes ago, JohnJ said:

Holes like this can often be the result of a fully 'decayed' marcasite (or some other iron based mineral) nodule.  The dark brown remnants look like they are visible in the large hole and as small inclusions in other spots.

There was some of the dark brown material in the hole, very soft, removed with a tooth brush. So that would explain it then?

[JohnJ]

2 hours ago, CWS said:

There was some of the dark brown material in the hole, very soft, removed with a tooth brush. So that would explain it then?

Sounds like classic iron based mineral decay.

[CWS]

2 hours ago, JohnJ said:

Sounds like classic iron based mineral decay.

Thank you. How would have happened, some sort of imperfection in the shell?

[JohnJ]

12 minutes ago, CWS said:

Thank you. How would have happened, some sort of imperfection in the shell?

 

The right combination of elements within the matrix filled chamber were the genesis for the iron based crystal growth.  Over the millennia, the ground chemistry dissolves the shell and increases the chemical reactions with the nodule in the internal matrix.