Cretaceous tooth

[FossilDAWG]

Last Sunday I stopped at an outcrop of the Maastrictian (late Cretaceous) Prairie Bluff Chalk in western Alabama.  About 3 meters below the top of the formation I encountered this tooth.  It was definitely in situ, I had to chisel it out.  It's 2.1 cm long, 1.6 cm wide at the base, and 0.7 cm thick at the base (so quite flat).  Despite some cracking the tooth is not distorted, it is actually flattened not compressed during fossilization.  One face is almost flat, and the other is curved.  Both sides are serrated until very close to the tip; there are 5-6 serrations/mm.  I have an idea of what this tooth is, or what I want it to be, but I have never collected one before so I'd like to get more experienced opinions.  One thing that is confusing about this, the Prairie Bluff is a fully marine formation, deposited well offshore in moderately deep water.  Associated fauna included a diverse array of marine bivalves, gastropods, echinoids, cephalopods (heteromorph ammonites including baculitids, Hoploscaphites, Discoscaphites, and Diplomoceras, as well as coiled nautiloids), and very scarce shark teeth, so it was definitely a fully marine environment.

 

So, what do y'all think?

 

Don

[Al Dente]

The serrations on the carinae look more beaded than like true serrations. I think this might be a flattened mosasaur tooth.

[Carl]

Seems too flat to be a mosasaur to me. And the curve would normally arc towards one of the carinae rather than perpendicualr to them. Maybe fish?

[indominus rex]

Something also tells me it is a flattened mosasaur tooth, the way the serrations are aligned seems like a Mosa tooth to me. Not 100% sure though, but nice find.

[FossilDAWG]

A closer look at the serrations:

 

[Troodon]

I dont get a moasaur feeling on this tooth,  to compressed but stuck with an alternative.

 

The list of canidates should be in this paper have you seen it?

https://www.researchgate.net/publication/272508435_An_Overview_of_Late_Cretaceous_Vertebrates_from_Alabama

[JarrodB]

The shape reminds me of a Protosphyraena tooth but they are not serrated. 

[Miocene_Mason]

Just now, JarrodB said:

The shape reminds me of a Protosphyraena tooth but they are not serrated. 

About to say the same thing, perhaps a close relative?

[Smoosh]

Maybe Enchodus ferox? I think that species had fine serrations.

[non-remanié]

The flatness may be somewhat deceptive if this is just the tip of a really large mosasaur tooth.  But it looks hollow and matrix filled which doesn't seem possible if it's mosasaur.   Is it matrix filled?  I think a brighter version of your third pic might be quite helpful as well. 

[Al Dente]

The close up photos of the serrated edge makes me think it is fish, not mosasaur like I originally thought.

[Anomotodon]

That is an interesting one! Can we see pictures from the basal part of the tooth to determine if it has a pulpar cavity? If it does, then it is definitely reptilian, although I am leaning more towards Squalicorax anterior, maybe even slightly pathologic. Looks very close to S. falcatus, compare with the tooth in the second row on the picture below (taken from here).

S. falcatus lived earlier in the Cretaceous and according to the paper Troodon posted, there are Santonian sediments with S. falcatus present in Alabama. Are you sure it is Maastrichtian? Although even if it is it still could be S. pristodontus, but they are usually more massive.

Protosphyraena teeth have a flat profile and a perpendicular distal carina, below are some examples from my collection.

 

[frankh8147]

I'm having trouble here too. Are we sure this can't be a theropod tooth? I Don't think it's Squalicorax (serrations and overall look is different) and the only fish I can think of from the east coast Cretaceous with serrated teeth is Enchodus Ferox. Depending on the position of the tooth, their teeth can really vary significantly in shape but I just don't see an eonchodus tooth here (and if it is indeed hollow, that would eliminate enchodus altogether). It really does have a 'fishy' look to it though..

 

 

[frankh8147]

Here is the best i could come up with for the possibility of enchodus. 

 

Enchodus fangs do tend to, from my experience, be flat on one side and rounded on the other which matches well. E. ferox (left, first picture) also does have some serrations. The second picture is there just to compare the shape of them to your tooth.

[Al Dente]

I have an odd fish tooth from the Maastrichtian Peedee Formation from North Carolina that is serrated. This tooth is 20 millimeters long and resembles some type of Scombrid tooth. I tried to photograph the serrations but it doesn't do them justice. There is thickened enamel on the carinae and on the tip.