Bone or osteoderm of some sort?

[Fin Lover]

I found this in a creek in Summerville, broken by some heavy equipment.  I don't normally keep random bone, but this was interesting.  Any idea what it is?  Currently about 4.3 inches by 2.5 inches.  It is thickest in the middle (12 mm) and thins out as you move towards the edges (like a pancake).  It is not like any osteoderms I have found yet, but I don't know what bones would be shaped like this, either.  Thank you!

 

[val horn]

I have no idea what you have found.  I have not seen that trabeculation pattern before, It doesnt look like the bone I am used to.    Could it be calcified cartilage-- shark or ratfish??

[Brandy Cole]

Looks like permineralized trabecular bone to me, but I've never seen anything quite like it.

[Mahnmut]

Hi, 

very interesting piece.

There is one thing that irritates me: The surface visible in the first pics looks like a natural surface, somewhat osteoderm-ish with the dimples etc. . But what would be spongiosa is open to the surface, like it never is in a living or intact bone. In the cross-section, you can also see that the pores from the surface are part of elongated "tubes" perpendicular to the flat surface.

I have no experience with fossil cartilage. Looks different from examples of prismatic cartilage here on the forum. I agree with "not the bone I am used to".

Curious what others will have to say.

Best Regards,

J

[val horn]

https://www.researchgate.net/figure/calcified-cartilage-and-dermal-denticles-of-Ischyrhiza-mira-leidy-1856-from-Upper_fig3_324114326  

[Done Drillin]

Here’s a piece that has somewhat similar trabeculations to yours from the St Marys River - I had identified it ( maybe) as a basal piece of a ray mouthplate with all the “teeth” broken or worn off. Certainly interested to know what it actually is !