[Big Brook] Small curved tooth with conical base and no visible carinae. Missing tip, but seems too narrow for mososaur - possible plesiosaur?

[TRexEliot]

Found this on a trip to Big Brook yesterday and having a tough time figuring out what it is. The tooth is missing the tip, but appears to be quite narrow, with a strong curve that would eliminate xiphactinus as a possibility. It looks too narrow to me to be a mosasaur tooth and has no visible carinae. Is there any chance it could be a plesiosaur tooth? Thanks for the help!

[Fossildude19]

Is the opening at the base oval, or circular?  Hard to tell from these photos.

 

[TRexEliot]

@Fossildude19 here is a better close up of the opening at the base. Seems to be oval. What does oval vs. circular tell you?

Edited April 24, 2023 by TRexEliot

[Notidanodon]

Hmm tough call but I think possibly ischyriza saw fish rostral tooth

[Al Dente]

The base of the tooth reminds me of Pachyrhizodus.

[TRexEliot]

@Notidanodon I considered that, but I've never seen a saw fish rostral tooth with that conical base before. They can sometimes be very hard to distinguish from mososaur teeth when they're partial like this, but is it possible for them to have that cone like a mososaur tooth as well?

[TRexEliot]

Anyone else have any thoughts on this? I'd at least like to clear up whether it's most likely reptile or sawfish

[Notidanodon]

On 4/26/2023 at 1:53 AM, TRexEliot said:

@Notidanodon I considered that, but I've never seen a saw fish rostral tooth with that conical base before. They can sometimes be very hard to distinguish from mososaur teeth when they're partial like this, but is it possible for them to have that cone like a mososaur tooth as well?

 I don’t have enough specimens to compare I’ll see if I can get my hands on some  

[TRexEliot]

 

19 minutes ago, Notidanodon said:

 I don’t have enough specimens to compare I’ll see if I can get my hands on some  

 

After comparing against a lot of the sawfish rostral teeth in my collection, I feel very confident in saying this isn't one. None of them have the conical indent at the base, and the material looks very different.

[pachy-pleuro-whatnot-odon]

On 4/25/2023 at 1:30 AM, Al Dente said:

The base of the tooth reminds me of Pachyrhizodus.

 

Yeah, definitely see where you're coming from with the straight side to the circumference of the base of the tooth. I think you're right in this being a Pachyrhizodus spp. tooth, as in plesiosaurs of this age, I'd expect to see some kind of dental ornamentation in the sense of striations, which I'm not seeing here...

 

 

[TRexEliot]

Hm, it doesn't really look like any fish material I've seen in the brook. Two people on r/bigbrook are suggesting some type of crocodilian

[pachy-pleuro-whatnot-odon]

6 hours ago, TRexEliot said:

Hm, it doesn't really look like any fish material I've seen in the brook. Two people on r/bigbrook are suggesting some type of crocodilian

 

Quite possible too, seeing as how the dental cavity looks... The tooth also seems a bit too round for Pachyrhyzodus spp. maybe. Then again, with such a poorly preserved partial tooth, I'm not sure whether a definite answer is attainable. Below are a couple of Pachyrhyzodus spp. teeth for comparison.

 

 

(source)

 

 

 

(source)

 

 

One argument for crocodile over Pachyrhyzodus spp. is the root structure, which seems lacking in most fish teeth...

[jdp]

Not Pachyrhizodus. The striations in the enamel are pretty conspicuously reptile in nature. I'm thinking plesiosaur isn't an unreasonable guess.

[Al Dente]

1 hour ago, jdp said:

Not Pachyrhizodus. The striations in the enamel are pretty conspicuously reptile in nature. I'm thinking plesiosaur isn't an unreasonable guess.

 

I think we are looking at cracked and weathered enamel, not striations. I've seen that on several different types of fish teeth that have thin enamel. It would be an awfully tiny plesiosaur. I'm guessing this tooth is only a couple millimeters long.

[TRexEliot]

 

17 minutes ago, Al Dente said:

 

I think we are looking at cracked and weathered enamel, not striations. I've seen that on several different types of fish teeth that have thin enamel. It would be an awfully tiny plesiosaur. I'm guessing this tooth is only a couple millimeters long.

 

The tooth is about 3/4 of a centimeter, but obviously missing the tip.

[Al Dente]

1 hour ago, TRexEliot said:

 

 

The tooth is about 3/4 of a centimeter, but obviously missing the tip.

 

Pretty small. About the same size as the ones in the photos that pachy-p posted above.

[pachy-pleuro-whatnot-odon]

7 hours ago, Al Dente said:

I think we are looking at cracked and weathered enamel, not striations. I've seen that on several different types of fish teeth that have thin enamel. It would be an awfully tiny plesiosaur. I'm guessing this tooth is only a couple millimeters long.

 

While I don't think the tooth would be too small for plesiosaur by definition (smaller species did exist, even into the Cretaceous, as did juveniles, of course), I do agree that the tooth enamel looks cracked, rather than having striations. You see this on reptile teeth too, sometimes. Initially, I was also misled by the way the enamel has cut away in places to give the impression of striae, though ultimately believe that what can, at first glance, be confused for striations are, in fact, just the unweathered enamel lying on top of what's left of the dentine (?) core of the tooth (in fact, I had already started writing my argument against Pachyrhyzodus sp. when I noticed this mistake in my interpretation). Moreover, plesiosaurian striations would look different from the way the imagined striae on this tooth do. So, I too, remain with Pachyrhyzodus sp..

[TRexEliot]

How rare are Pachyrhyzodus teeth in big brook? I don't think I've ever even seen them mentioned on most of the common sites about big brook fossils.

[pachy-pleuro-whatnot-odon]

1 minute ago, TRexEliot said:

How rare are Pachyrhyzodus teeth in big brook? I don't think I've ever even seen them mentioned on most of the common sites about big brook fossils.

 

The links I referenced above all pertain to fossil sites in New Jersey, which, I'd presume, includes Big Brook...