Cretaceous Jaw.....fish,mosasaur?

[John S.]

Found some things this am. I assume I have a jaw fragment and mosasaur tooth? Thoughts on the jaw? Thanks.

Late cretaceous, Eagle Ford, 86-92 mya, north central tx.

[John S.]

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[Diceros]

John S. - I've seen the one in your hand above before - I thought at first it was the ant. premaxilla, but then noticed Meckel's groove (a remnant of the original cartilage lower jaw - what shark and ray lower jaws are made up of), towards the bottom in the left pic. It's the ant. part of the rt. dentary (lw. jaw) of a big predaceous bony fish called Pachyrhizodus. There are, unfortunately, a million species, and it needs a revision. This is a big one, like P. caninus Cope, 1872. The really big lt. Turonian ones (like P. leptopsis) were confused (frequently) with early mosasaur teeth (there actually are m.-lt. Turonian mosasaur teeth, but they're rare).

Mike Triebold has now reconstructed a 3-D skeleton of a big Niobrara Pachyrhizodus, which is both incredible, and way ahead of the literature. Museums sometimes buy several from him, then mount them as a big scary school of hungry fish. That guy's a genius.

[Foshunter]

John,

Diceros is correct with ID, these fish have teeth, especially found as a single specimen, can easily be confused as Mosasaur. Pictured is a partial jaw specimen from the Niobrara-----Tom

[John S.]

Thanks for that great information guys! I can see how that can be confused with mosasaur..