Bone fragment or funny rock

[Alex E]

This was found by my partner loose on the foreshore at Folkestone (UK), near Copt Point. Presumed geological strata is Cretaceous - Middle/Early Albian.

I've very little experience with fossilized bones I'm afraid and suspect this is just a rock formation, but figured it was worth a check just in case

 

 

[Fossildude19]

Cropped and enlarged:

 

 

 

 

 

[Calli99]

I can see boney texture, but need better quality photos from more angles to be sure. Marine reptile bones have been found at Folkestone, but rarely.

[pachy-pleuro-whatnot-odon]

As @Calli99 said, the structure of the specimen is reminiscent of bone and marine reptile bones have been uncommonly found at Folkestone (most recent thing I heard of were ichthyosaur remains a few months back). However, this piece is, unfortunately, too small and worn to identify, I'm afraid...

Edited October 23, 2021 by pachy-pleuro-whatnot-odon

[Rockwood]

Ya,    I'm thinkin' no. It isn't a hard no though. 

[Tim Delaney]

Collar Bone?

[Alex E]

Thank you for the replies, I was leaning towards no as well, and I didn't really expect an ID proper either considering size and condition.

Should I expect bone fragments in general to have a semi-porous structure at least on visual inspection like non-fossilized bones do? Or does the porous structure typically get "filled up" with mineral sediment during fossilization? If porosity is expected, then I think the photos might be deceptive as there's very little if any of that and I guess to me it bears more of the structure of a sedimentary rock.

[Calli99]

It kind of depends on the preservation as to the porosity of the bone. I think you should mostly expect significant and obvious porosity, but some bones - especially those that have been significantly beach rolled - may feel smooth to the touch but it is still possible to see porosity.

 

If I were you I would keep this item, maybe take it to a museum if you can. I haven’t even found so much as a fish vert at Folkestone, so in my view any chunk of potential bone is worth keeping, even if it turns out to be unidentifiable.

 

This piece of dino bone has been very beach rolled, it feels completely smooth but you can clearly seen bone texture.

 

This piece of turtle bone has been less worn and is more obviously porous.

Edited October 24, 2021 by Calli99

[pachy-pleuro-whatnot-odon]

5 hours ago, Alex E said:

Should I expect bone fragments in general to have a semi-porous structure at least on visual inspection like non-fossilized bones do? Or does the porous structure typically get "filled up" with mineral sediment during fossilization? If porosity is expected, then I think the photos might be deceptive as there's very little if any of that and I guess to me it bears more of the structure of a sedimentary rock.

 

I'm afraid the situation is not quite as simple as @Calli99 suggests, as there are as many different types of bone preservation as there are bone histologies. In a general sense: yes, you'd expect to see the porous structure of bone's internal vascularization (sometimes referred to as a "honeycomb structure"), which may or may not be filled in with a variety of minerals (a common mode of preservation is black bone with either white dots or white stripes, depending on the angle at which the bone was cross-cut). But first and foremost this also depends on the type of bone: long bones and vertebrae will exhibit this kind of structure, whereas skull bones and other flat bones will have a much more solid appearance without too much vascularization going on.

 

That's the absolute basics, and mostly applies to land animals. For secondarily aquatic organisms have much denser bone to help them achieve neutral buoyancy. This increased denseness of the bone can be achieved in two different ways: either by thickening the outer layer of bone - known as cortical or lamellar bone - a condition referred to as pachyosticity, or by increasing the density of vascularization in the cancellous bone at the core, a condition referred to as osteosclerocity. Both of these conditions may also occur together, in which case they're referred to as pachyosteosclerocity. Only cancellous bone shows the typical "honey comb" structure, with lamellar bone being built up in solid-looking layers. Cancellous bone can also be reworked into lamellar bone through bone remodelling during an animal's life. But, especially in marine organisms, bone may become so dense as to look almost solid, as is the case with the below cut and polished Brachypterygius extremus ichthyosaur vertebra from Oday, Abingdon, in the UK:

 

 

A special case concerns that of pterosaurs, which bones are hollow to reduce weight for flying. As such, their long bones have (proportionately) paper-thin walls (cortical bone) with near to no vascularization at the core. Instead, they have a complex pattern of bone struts that support the walls and keep them in place.

 

 

Lastly, I looked up the recent find of a bit of ichthyosaur jaw from Folkestone I mentioned earlier (find was made in August, this year): here it is.