Micro Stone City shark teeth

[jikohr]

Hi everyone,

I'm trying to id some very small shark teeth for an independent research paper I'm writing and am a little unsure on my ids. I took some photos of some typical specimens and was hoping to get some feedback. The scale bar is mm. I put what I think the species is with each group of photos. Any feedback and tips for differentiating these species would be greatly appreciated.

[Al Dente]

Most of these look like Physogaleus secundus. We would need to see the labial sides to rule out some other possibilities such as Galeorhinus.

[jikohr]

Thanks! I'll post some better pics with both sides later today. How does one tell the difference between Galeorhinus and Physogaleus?

[Searcher78]

IDs look good to me.

[Searcher78]

Don't know if this helps...…….hope it does!

[jikohr]

Thanks!

I do have a couple questions.

Does the root bulge out on all Physogaleus teeth regardless of the jaw position?

When identifying Pachygaleus I always look for a main cusp that is much more stubby and short than the other two species, is that accurate?

[Searcher78]

52 minutes ago, jikohr said:

Thanks!

I do have a couple questions.

Does the root bulge out on all Physogaleus teeth regardless of the jaw position?

When identifying Pachygaleus I always look for a main cusp that is much more stubby and short than the other two species, is that accurate?

Yes, for Pachygaleus, shorter main cusp. The majority of Physogaleus teeth I have seen have protruding (thick) root. I’m not sure about all jaw positions though. The only Physogaleus I find in the areas I hunt is the “contortus”.

[Al Dente]

Pachygaleus and Galeorhinus have a bulge of enamel that hangs over the root on the labial side. Physogaleus doesn’t. You can see the bulge in the photos Sercher78 shared.

[jikohr]

23 minutes ago, Al Dente said:

Pachygaleus and Galeorhinus have a bulge of enamel that hangs over the root on the labial side. Physogaleus doesn’t. You can see the bulge in the photos Sercher78 shared.

I read that elsewhere and was kind of confused by it. Is the enamel bulge near the ends? Because I saw a slight bulge in the center of the enamel as well on Physogaleus. Also Here are better pictures that show all the labial faces.

[Al Dente]

On 3/3/2021 at 5:19 PM, jikohr said:

Is the enamel bulge near the ends?

 

It should go all the way across the tooth. Here is the only one of your teeth that I see with an enamel bulge.

 

 

[Al Dente]

Here are many examples of Middle Eocene Physogaleus secundus. These are from the Claiborne Group of Alabama, the same age as your teeth. I've included a picture of the reference that this picture came from. It's a good paper.

 

 

 

 

[jikohr]

Thank you so much! this helps alot!