Eocene shark tooth, Whiskey Bridge

[Jared C]

A few weekends ago, driving to A&M for a gymnastics meet  (I'll be transferring there this fall!), I noticed a very familiar looking bridge from this forum, and the sign confirmed that barely 20 minutes away from the heart of campus is the famous Whiskey Bridge. I had no idea, so this was a very pleasant surprise. On the drive back, I decided to hit the bridge bright and early.

 

Found a few cool inverts that are easy enough to ID with the good guides for them, but the sharks of whiskey bridge seem to be poorly written up. In fact, I couldn't find any good guides that compiled more than on just a couple of the Texas Eocene sharks. Are they more poorly understood than their texas cretaceous counterparts? Or is there just less public interest in them?

 

Here's the mystery tooth. Stone city formation of the (middle?) Eocene.

If anyone knows of a good online or paper guide for the marine vertebrates of whiskey bridge or the Texas Eocene in general, please let me know. 

[historianmichael]

This paper might be helpful. It is on chondrichthyes and osteichthyes of the Claiborne Group in Alabama

 

https://europeanjournaloftaxonomy.eu/index.php/ejt/article/view/819/1913

Edited April 5, 2022 by historianmichael

[Al Dente]

It could be a lateral Negaprion gilmorei, aka Carcharhinus gilmorei.

[siteseer]

On 4/4/2022 at 9:09 PM, historianmichael said:

This paper might be helpful. It is on chondrichthyes and osteichthyes of the Claiborne Group in Alabama

 

https://europeanjournaloftaxonomy.eu/index.php/ejt/article/view/819/1913

 

Thanks for the link.  That paper has an excellent review of Negaprion gilmorei from its description to more recent comments. 

 

At first glance, the tooth appeared to be either a Sphyrna or Carcharhinus tooth but the age is a little too ancient for the former.  I agree with Al Dente that it's an N. gilmorei tooth.

[Jared C]

On 4/4/2022 at 11:09 PM, historianmichael said:

This paper might be helpful. It is on chondrichthyes and osteichthyes of the Claiborne Group in Alabama

 

The fauna that this paper covers... is it possible to find the same stuff in the middle eocene in texas? I notice that there are quite a few charismatic sharks like Otodus and Hemipristis included here - one would think that perhaps they could be found in Texas as well, considering places like whiskey bridge are also the claiborne group... but I've never heard of anything like that being found here, and due to how coveted those sharks are I find it hard to believe that people wouldn't be talking about them.

 

If the claiborne fauna here vs in alabama are different, why is that so? 

 

[Plax]

Not sure of the age of the Whiskey Bridge site but the paper is referring to Otodus auriculatis I believe. Formerly Carcharodon then Carcharocles auriculatus. Otodus obliqua, the original Otodus, is slightly older at late Paleocene to early Eocene.

  Not sure why ya'll don't get Hemipristis.

[JohnJ]

@dinodigger 

Chris's guide is light on vertebrates, but full of good information, otherwise.  

 

Whiskey Bridge guide_FLIS_2_23_15.pdf

[siteseer]

7 hours ago, Jared C said:

The fauna that this paper covers... is it possible to find the same stuff in the middle eocene in texas? I notice that there are quite a few charismatic sharks like Otodus and Hemipristis included here - one would think that perhaps they could be found in Texas as well, considering places like whiskey bridge are also the claiborne group... but I've never heard of anything like that being found here, and due to how coveted those sharks are I find it hard to believe that people wouldn't be talking about them.

 

If the claiborne fauna here vs in alabama are different, why is that so? 

 

 

You might get some of the same or a lot of the same sharks but Whiskey Bridge might be at least one million years older or younger than any of the Alabama sites (Little Stave Creek, Point-A Dam, etc.).  One might represent  a less saline/brackish or shallower environment so a smaller diversity or simply smaller sharks might be the rule.  It is my understanding that shark teeth are less common and less diverse at Whiskey Bridge than what is found at Point-A Dam but maybe it's just a matter of someone spending more time to get a decent sample of everything that can be found there.

[CDiggs]

I found this paper on the Claiborne Group that I found really interesting when trying to learn more about the paleoenvironment at Whiskey Bridge. The TLDR; Sub-tropical, ~40-60 meters of water if I remember correctly.

https://www.researchgate.net/publication/240377215_Petrology_and_palaeoenvironmental_significance_of_authigenic_iron-rich_clays_carbonates_and_apatite_in_the_Claiborne_Group_Middle_Eocene_NE_Texas

 

When I went looking for the link to paper above I came across this one too which I haven't read yet but it's more recent so I'll definitely be reading this one soon. 

https://www.researchgate.net/publication/260120344_Mineralogy_and_Geochemistry_of_the_Main_Glauconite_Bed_in_the_Middle_Eocene_of_Texas_Paleoenvironmental_Implications_for_the_Verdine_Facies