cold front creek stomping in central texas

[Jared C]

Recently I've been researching a late cretaceous texas shark that I've never even heard of until two nights ago. I'm already a bit of a night owl (as you might see by the timestamp, I'm writing this well past midnight already ), but these last two nights spent researching and investigating potential spots have been LATE ones, around 3 AM - I guess I've really been bitten by the bug here.

 

The shark in question is Pseudomegachasma, specifically Pseudomegachasma comanchensis (for my area). It's thought to be a roughly 15-20 foot filter feeder, related to sand tiger sharks of all things (family Odontaspididae), and its small teeth bear an extreme (yet superficial) resemblance to those of the modern Megamouth shark, Megachasma. Pseudomegachasma was only described in 2015. Its teeth are very rare, but specimens existed already for years - it was simply assumed that they were beaten up specimens of a related shark, Johnlongia (which I also never heard of until lately).

 

What really excited me was finding that a tooth used in the paper came from Eagle Ford strata (Bouldin Flags member, specifically) in Williamson county, of all places. I actually obtained coordinates eventually, but those coordinates were only specific to two decimal places, and so not as useful as I hoped. There used to be a massive Eagle Ford bonanza in Round Rock (just north of austin), but it was covered up by construction... so was hope lost?

 

No!

I actually knew of one permanent, super isolated exposure of what I'm 95% sure is Eagle Ford, in Williamson county. Furthermore, those vague , blanket coordinates made reasonable sense with this exposure. So now, my mission was to investigate this exposure in a new light, looking for both the tiny (8 mm ) teeth of Pseudomegachasma and also for ammonites for their use as index fossils, to determine if I'm really in the late Cenomanian/early Turonian Bouldin Flags member like I'd need to be.

                                                                       

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Today was absolutely frigid (for texas standards at least), and way too cold for creek stomping. Nonetheless, I donned many layers and threw on my sandals. Walking through the water was quite painful - probably not a big deal up north, but here that's an uncommon experience. After a stretch of sharp inhales and curses, I finally waded out onto my first gravel bank. It produced a small Ptychodus tooth - I still need to look closely at it to try and pry a more specific ID.

 

Soon after, on the next bank, I noticed a bovid tooth. Upon closer inspection, it turned out to be bison, much to my surprise. All of the many bison teeth I've seen from central texas came from one specific creek - this was my first time seeing one elsewhere in the area.

 

I also saw two more shark teeth soon after - a small Cretoxyrhina mantelli and what *may* be Ptychodus anonymous, I'll take a closer look at it as well soon.

 

The cold was starting to weigh down on me, and I had work coming up soon, but then I thankfully a caught a break with at least one of my goals - finding an ammonite, washed out from the stumpy exposure, to make use of as an index fossil. My ammonite ID skills are among the worst on the forum I'm sure, so I'll be putting it up on fossil ID shortly. My hope is that this partial and impression will be enough.

 

This was the last of my finds of note today. If this exposure is indeed bouldin flags, I will be back with a microfossil vengeance.

 

 

Oh - and just to put into perspective how absurdly inappropriate my outfit was for wading in this weather today:

 

 

The three layers and beanie couldn't compensate... well worth it though.

 

Edited January 8, 2022 by Jared C
typos (you'd think I'd learn to reread by now, right?)

[Ludwigia]

2 hours ago, Jared C said:

Oh - and just to put into perspective how absurdly inappropriate my outfit was for wading in this weather today

 

Don't forget to don your nylons next time

[FranzBernhard]

4 hours ago, Jared C said:

 

"I´m dying".

Na, isn´t that bad, just your feet are going to fall off .

Anyways, thanks for sharing . I like your reports with all that background info and in-situ-pics very much!

I will skip my prospecting day tomorrow - too cold, perhaps also too much snow... 

Franz Bernhard

[RJB]

Very interesting report!

 

RB

[RuMert]

Nice report! Rubber boots would have made a huge difference

[Jared C]

7 minutes ago, RuMert said:

Rubber boots would have made a huge difference

If this wasn't an incentive to go buy some (or a pair of waders....) then I don't know what is

[fossilsonwheels]

I have 2, possibly 3 Pseudomegachasma from Russia, Melovatka Formation. Dr. Shimada helped me with those IDs on two of them. Good luck on your search. I’ve only seen US examples in published papers. Be quite a find if you are successful 

[FossilNerd]

Nice report Jared! Research and determination can pay off. Keep it up, and buy that set of waders. Your toes will thank you!

 

[erose]

Hard core...for sure.

 

Maybe next time find some old sneakers and socks and just have a towel and a warm change out ready in the car.

[digit]

+1 for waders (and possibly some heated socks as well).

 

Sounds like an excellent mission to find a rarity--good luck, we're all pulling for you!

 

 

Cheers.

 

-Ken

[fossilhunter21]

Nice report!

 

Definitely get some waders.

 

Thanks for sharing!

 

-@fossilhunter21

[BudB]

Ok, I got cold just reading and looking at that. Nice finds!