Seal Molar... Or Something Else?

[ShadyW]

So here's today's haul from the North Sulfur River and Post Oak Creek in North Texas:

At the North Sulfur River I found a quite nice Mosasaur vert and a really big Mosasaur tooth that's broken pretty much in half. The tooth is still a really nice find.

But it's the odd tooth that I found at Post Oak Creek, in amongst all the shark teeth that's really got me puzzled.

At first glance, I figured it was a Ptychodus tooth, or similar shell-crushing shark tooth, but it looks completely different from the Ptychodus teeth I find at Post Oak Creek. On these forums, what it looks most like is what you all identified as a seal molar. What do you think?

[Guest bmorefossil]

nice finds

[hybodus]

Shark tooth is a Water worn Ptychodus

[Guest N.AL.hunter]

I will start looking this one up. I have found quite a few water worn Ptychodus teeth, and they have never resembled that. I am not saying it isn't, but I'll do some research to see if I can find a better answer.

[Fruitbat]

Definitely not a seal tooth. The vast majority of the finds at the North Sulfur River are either Cretaceous, Pleistocene or Holocene. There were no seals in the Cretaceous (they hadn't evolved yet) and the Pleistocene/Holocene mammalian finds are all terrestrial (no ocean anywhere nearby during those time periods). So...since we've ruled out a seal...then what is it?

I suggest that it most closely resembles a Dasyatid ray tooth...albeit a very large one if the bone and mosasaur tooth are used for comparison. I don't guarantee that identification but the tooth characters seem to point in that general direction.

-Joe

[Boesse]

I would also mention that true seal postcanine teeth look markedly different, and have multiple cusps. This tooth does superficially resemble that of fur seals (not closely related to true seals), but 1) it was not a close enough match and 2) fur seals never made it into the north atlantic (and not much of the south atlantic on that same token).

Looks to me like some sort of an elasmobranch tooth, potentially a batoid tooth.

Bobby

[ShadyW]

Thanks for everyone's input so far.

Just to clarify and re-state my first post: this tooth was found at the Post Oak Creek site in Sherman, not at the North Sulfur River, if that changes anything.

From the particular location this came from at Post Oak Creek, I've also now found two mineralized vertebrae that are definitely not Mosasaur. I'll post pictures of them later today, but to me they look like possible turtle verts, although from their size (larger than that Mosasaur vert in the picture above) it would have to be a turtle on the scale of an Archelon!

[Fruitbat]

ShadyW...

The Post Oak Creek fossils are also Cretaceous so yours is still definitely NOT a seal. As for the possibility of Archelon vertebrae in the vicinity...the huge Archelon fossil on display at the Dallas Museum of Nature and Science (formerly the Dallas Museum of Natural History) came from an erosional feature near Fate, Texas so it certainly isn't beyond possibility that you could have similar fossils in Post Oak Creek.

-Joe

[ShadyW]

OK, here we go on the verts from Post Oak Creek.

The first one (on the left in the first picture) I already posted here, asking if it was a "toe bone". Since then, I noticed that it had matrix at two points at either end. Carefully removing this matrix, it has a hole right through it, making it a vert of some sort (makes sense with the worn ball at one end, and the shallow socket at the other). This means it's a pretty odd shaped vert - I know it's heavily worn, but the remaining original bone surface all around at some points shows that it was a long, thin, slightly curved shape when whole.

A few weeks later, on the same sand bank, I found the second damaged vert (on the right), with part of the vertebral process still intact, but much more worn than the first vert. Alongside it, I found this smaller bone (bottom of the first picture). I've found many bones of this general form at the North Sulfur River, but none at Post Oak Creek. Again, it's worn, but is it a bone from a flipper, or a badly worn vert?

As always, I'd really appreciate all your informed opinions (and wild guesses too!).

[ShadyW]

[ShadyW]

Oh, and my best ever Ptychodus tooth!

It's huge - I forgot a quarter for scale, but it's 1.5" at least, which is about 50% larger than any of my other 15 or 20 Ptychodus teeth from the same site. It's also in the best condition.