Absolutely Bizarre Jaw/Bone/Toothplate?

[LordTrilobite]

About two weeks ago I bought this bunch of Kem Kem chunkosaur pieces in the hope that something interesting might be in there among the nondiscript bone fragments. There were some things that were identifiable.

 

But this one piece completely baffled me when I looked at it more closely. I hadn't noticed it at first because it still had a bunch of matrix on it. But I soon saw some weird square shapes. These remind me of of the shapes some reptiles have under their scales on their skull. The bone piece already had a weird straight shape with a hollow in the middle. At first I assumed the hollow on the inside of the bone that was just exposed due to breakage. But I then cleaned it some more and a pattern emerged on the inside of the fold that I can only describe as a toothplate.

 

I'm almost positive this must be some kind of jaw piece with a strange tooth plate. I know Kem Kem is still very much a mystery. But I've never seen anything quite this thoroughly bizarre before. Has anyone ever seen anything similar to this?

 

Side with the "toothplate" visible as well as clear square shapes on the outside of the bone. It's still not completely clean, but the toothplate seems to extend futher into the fold.

 

Flat outside edge. The square shapes end in half circles on this side. The other side of the edge also has similar patterns but on a different scale and not as clear.

 

Other side with more subtle square shapes on a smaller scale.

 

Both broken sides to show the cross section. It's also slightly asymmetrical.

 

 

 

 

[westcoast]

What a strange piece. Can't wait to see what others have to say. Those small tubercles wouldn't look out of place on a placoderm! I'm obviously not going to be any help.

[non-remanié]

it's calcified cartilage, possibly from a sawfish rostrum such as onchopristis

[sagacious]

Interesting. Looks like chondrichthyan cartilage to me as well.

[GeschWhat]

What a fun interesting piece!

 

[marguy]

Hybodont, stingray caudal spine piece?

see: http://vertebresfossiles.free.fr/maroc/hybodonte_kemkem_maroc.html 

[Al Dente]

I agree with non-remanie, most likely part of a sawfish rostrum. Onchopristis is the common Kem Kem sawfish.

[LordTrilobite]

Thanks guys. Upon looking for Onchopristis rostrum on the internet it does indeed seem to be a close match. Though that structure on the inside still seems really weird.

[doushantuo]

pristidevol

[doushantuo]

mustseebelgsel

[doushantuo]

infraxyl

[doushantuo]

onch