BBC Focus Magazine

[Nails]

A new discovery negates the "inside-out" theory of tooth evolution.

New research on Early Devonian fish suggests that the world's first teeth evolved outside of the mouth.
Scales on the exterior of the prehistoric shark-resembling fish appear to have evolved into teeth.



The tooth-like lip and cheek scales were found in specimens of Ischnacanthid acanthodians similar to this one from the University of Alberta Laboratory for Vertebrate Paleontology

continued here: http://news.discovery.com/animals/teeth-prehistoric-111117.html#mkcpgn=rssnws1

[M Paul Lloyd]

Ah yes, I recall seeing a TV programme that showed how the skin of a Shark is covered in what are in effect variations on their teeth.

Well found Nails.

[...]

the scales on sharkskin are called "dermal denticles" and denticles translates as tiny teeth

[M Paul Lloyd]

That makes sense @@.

[Jamie]

It was on that 'Inside Natures Giants' I think. Had a theory about how jaws evolved from gill cartilage too.

[M Paul Lloyd]

Yes, that's the one.