A walk in the Austin Chalk

[Jared C]

For whatever reason, I used to completely dismiss the Austin chalk as a formation of any interest. I viewed it almost through the same lens that I view the Edwards formation, as if it was some barren uninteresting hinderance that gets in the way of cooler formations. Accidentally finding a large Parapuzosia ammonite in it once changed that a bit, but for the most part I still ignored it...

 

Turns out I was just looking in the wrong places, and had very little understanding of its members. @LSCHNELLE recently explained a lot of it better to me, and so equipped with new knowledge I decided to try and discover a member of the Austin Chalk I've been wondering about for a while now, which I always falsely assumed was its own formation.

 

I found myself deep in a Travis county creek, following very specific instructions I had read on an old thesis from the 80's I found online. To avoid being too long winded - nothing stood out to me as different in the geology, so I think that the vertebrate rich member I was seeking still eludes me. Yet, I wouldn't say I was skunked, because I found some very interesting invertebrates that even a simpleton like myself can appreciate 

 

My first find had me cheering and jumping, partly because of how just picture perfect the insitu was, but mostly because it was just an aesthetic looking echinoid I haven't seen before.

 

Here it sat below, as I originally saw it:

 

 

Fortunately, what's left in the matrix I believe is still in great detail. It's just on a smaller-than-it-looks exposed portion where the wear took a toll, as you will see at the end when I show more photos.

 

For another hour and half beyond this, I was just sloshing my way through the water, very slowly, admiring the highly fossiliferous limestone as I went. Usually when I scout a new spot, it ends up being more exploring than actual hunting, and yesterday was no different. 

Close to my turn around spot, I for whatever reason took strong notice of inconspicuous looking pebble lying loose on its own. Picking it upon a whim, I was surprised to see it was another echinoid of the same type I found earlier, albeit in worse condition. Pictures all at the end.

 

Walking back was a serene vibe with few fossils - I was distracted by the new greenery that's been blooming lately. When I got back to where I found the  first echinoid, I decided to poke around a bit more, and was surprised to find two ammonites - one large (Mortoniceras?) which I removed, and a much smaller ammonite as well. 

 

Results below! No vertebrates but these were well worth it! @JamieLynn put together a phenomenal guide of the inverts by formation that we can find in our central texas stratas, but I wasn't able to find these echinoids in it. I'm aware they need prep, but if you know what they are already please chip in!

 

Results below:

Echinoid #1:

 

 

 

 

Echinoid #2 - While it's in worse shape than even the first, I think the substantial attached matrix has protected a lot of it. We'll find out when it preps!

 

 

Larger ammonite I removed - glue will come to the rescue here. I'm rather sure that the inner coils are preserved under that!

 

Smaller ammonite below:

 

This was just one day sandwiched into what is so far a very busy weekend for me on the paleo front - lots of exploring, and also some good work brewing on two interesting, older vertebrate finds. I'll update this post when i eventually manage to get these echinoids cleaned - the hard limestone they're in will be tough for hand tools - perhaps this is my signal to finally buy  a scribe

[caterpillar]

Nice Cidaridae. Bravo!

[JamieLynn]

wow...congrats! Yes, I HAVE seen a partial cidarid echinoid come out of Austin Chalk but I didn't find it myself and don't have pics of it. They are there but are very few and far between. 

[grandpa]

Jared, you seem like such an intelligent, vibrant, charming young man with a strong enthusiasm for paleontology.  That's why I cannot understand, for the life of me, your bigotry against the wonderful world of invertebrate fossils. 

 

Grandpa (lover of the inverts)

[Jared C]

6 hours ago, caterpillar said:

Nice Cidaridae. Bravo!

thank you! Matches well

[Jared C]

20 minutes ago, grandpa said:

Jared, you seem like such an intelligent, vibrant, charming young man with a strong enthusiasm for paleontology.  That's why I cannot understand, for the life of me, your bigotry against the wonderful world of invertebrate fossils. 

 

Grandpa (lover of the inverts)

I'm learning slowly! This is a big field 

[Jared C]

1 hour ago, JamieLynn said:

wow...congrats! Yes, I HAVE seen a partial cidarid echinoid come out of Austin Chalk but I didn't find it myself and don't have pics of it. They are there but are very few and far between. 

Thank you - I had my suspicion these echinoids weren't common, because usually it's much older formations that I see people hunting and talking about echinoids. I couldn't recall ever seeing a post about an echinoid hunt in the Austin chalk. However, I wasn't aware of the extent until now. Beginners luck I think

[JohnJ]

Outstanding finds!!  Well done, sir.

 

Was this from the Dessau Formation?

 

@Uncle Siphuncle

@erose

[DPS Ammonite]

1 hour ago, Jared C said:

However, I wasn't aware of the extent until now. Beginners luck I think

Here is a post about echinoids and ammonites from the Austin Group:

 

 

[Jared C]

1 hour ago, JohnJ said:

Outstanding finds!!  Well done, sir.

 

Was this from the Dessau Formation?

 

@Uncle Siphuncle

@erose

That's exactly the formation I was hunting, but I didn't think I was successful. Perhaps I was! I just need to get better at differentiating these members based on their appearance.

 

Edit: I recognize Exogyra laeviuscula from the area that Dan mentioned to be index fossils for the Dessau. There weren't many but I did see a few that looked like these

Edited April 3, 2022 by Jared C

[Uncle Siphuncle]

I have found cidarid spines and plates in the Dessau down here, but no whole tests.  Well done.

[LSCHNELLE]

You have a lot of beginners luck - rare whole citarid echinoids on your first try in the Austin Chalk!  So, I think we can't call you a "beginner" anymore.  Either way, thanks for taking up the Austin Chalk vertebrate Central Texas challenge!  I may need to join you soon - to "help" you find that second Ptychodus rugosus dentition from Texas!   At least with your sharp eyes, I might be able to claim partial credit. 

[Jared C]

14 minutes ago, LSCHNELLE said:

You have a lot of beginners luck - rare whole citarid echinoids on your first try in the Austin Chalk!  So, I think we can't call you a "beginner" anymore.  Either way, thanks for taking up the Austin Chalk vertebrate Central Texas challenge!  I may need to join you soon - to "help" you find that second Ptychodus rugosus dentition from Texas!   At least with your sharp eyes, I might be able to claim partial credit. 

I’d look forward to it!

[DPS Ammonite]

Jared, have someone help you prep those two cidarid echinoids. They are iconic and may be rare species. I would not want to practice my crude prepping skills on either one of them.

Edited April 3, 2022 by DPS Ammonite

[Mark Kmiecik]

4 hours ago, Jared C said:

I'm learning slowly! This is a big field 

Big enough to become permanently lost in. 

[Jared C]

1 hour ago, DPS Ammonite said:

Jared, have someone help you prep those two cidarid echinoids. They are iconic and may be rare species. I would not want to practice my crude prepping skills on either one of them.

I agree. I’d be uncomfortable doing that was well. I think I’ll send them to Kris

[Uncle Siphuncle]

21 hours ago, Jared C said:

I agree. I’d be uncomfortable doing that was well. I think I’ll send them to Kris

Jared, you live in a pretty good area, paleo wise.  In some ways I think San Antonio drew the short paleo straw compared to other major cities in Texas.  We don't have all the Austin members present that you do in the type area, and bone, at least in my personal experience, doesn't seem very prevalent in the Austin of the San Antonio area.  All of the lamniform shark teeth I've seen in my local Austin are enamel only, with roots either broken off, or in many cases dissolved away, leaving a hollow enamel "shell" only.  If taphonomic conditions were that acidic or harsh on bone, that may explain why I never see Austin fish or mosasaur material down here.  

 

Our Eagle Ford exposures are pretty pitiful too.  I have found some teeth in decent condition, including a number of Ptychodus anonymus, but scant surface expression of tooth bearing horizons prompts me to head north when I want teeth.

 

Our local Buda and Edwards are tough hunts as well, and our Walnut produces some echinoids, but is very thin.  No Ozan here either.  There are still some goodies to be had, but I find many formations to be more reliable if I'm willing to travel to your side of the San Marcos Arch.

[LSCHNELLE]

Pretty good summary @Uncle Siphuncle. I would add that in general the Uvalde, Bracketville, & Del Rio area (even though mainly private land) would also have great opportunities for vertebrates in the Eagle Ford to Basal Austin Chalk.  You probably know much better than I.  I have only tried one Eagle Ford highway cut in Del Rio only with no success and I couldn't get access in Uvalde. From Austin and Round Rock north, then skipping over most of Waco, I think the odds of vertebrates are much better. But, not in the Austin Chalk.  It's just tough.  Vertman proved that in DFW area over 100 days in 2013.

[jpc]

Excellent finds... but this quoted from your opening paragraph:

"Accidentally finding a large Parapuzosia ammonite in it once"

 

How large is large? These things get to be 4, 5 + feet in diameter

[DPS Ammonite]

58 minutes ago, jpc said:

Excellent finds... but this quoted from your opening paragraph:

"Accidentally finding a large Parapuzosia ammonite in it once"

 

How large is large? These things get to be 4, 5 + feet in diameter

If complete, the genus is thought to have been 8.5  to 11 feet across.

 

https://www.fossilera.com/pages/what-is-the-large-ammonite-ever-found

[Jared C]

3 hours ago, jpc said:

Excellent finds... but this quoted from your opening paragraph:

"Accidentally finding a large Parapuzosia ammonite in it once"

 

How large is large? These things get to be 4, 5 + feet in diameter

I should have rather worded it "large ammonite, from the genus Parapuzosia". While the partial I found was big, it wasn't big for the genus

 

2 hours ago, DPS Ammonite said:

If complete, the genus is thought to have been 8.5  to 11 feet across.

 

... as is seen here. However, this refers to Parapuzosia seppenradensis, which I don't believe is found in Texas. In Texas, the ones I know of are P. bosei and (P. americana?)

 

P. bosei was substantially smaller. My specimen still doesn't stand out for P. bosei though. Here's the trip report from when I found it, with photos. @JohnJ has some examples of larger Texas Parapuzosia in his Ammonites album.

 

[Uncle Siphuncle]

19 hours ago, LSCHNELLE said:

Pretty good summary @Uncle Siphuncle. I would add that in general the Uvalde, Bracketville, & Del Rio area (even though mainly private land) would also have great opportunities for vertebrates in the Eagle Ford to Basal Austin Chalk.  You probably know much better than I.  I have only tried one Eagle Ford highway cut in Del Rio only with no success and I couldn't get access in Uvalde. From Austin and Round Rock north, then skipping over most of Waco, I think the odds of vertebrates are much better. But, not in the Austin Chalk.  It's just tough.  Vertman proved that in DFW area over 100 days in 2013.

I believe that the complete Ptychodus skeleton that was excavated, sold to Tom Lindgren, shipped north, stolen and recovered months later was originally discovered out between Uvalde and Del Rio in the interval you mentioned.  And if memory serves, I've heard of a partial ichthyosaur discovered in the Kef near Del Rio.  But as you found out, the overwhelming majority of acreage out that way is tied up in cattle and hunting ranches, both big business, generally with little use for fossil carpetbaggers like us.  

 

As for Kef road cuts, they are easy to find out by Del Rio and beyond, with very distinct lithology from the underlying Buda and overlying Austin.  You can trace the flaggy limestones for miles, and I've poked around in them quite a bit, but visions of Allocrioceras and Ptychodus dancing in my head never amounted to anything but a sack-o-woe, with net zero personal finds from those flags.  There are certainly finds to be made, but I lacked the intel and determination to pull together a successful trip to date. 

 

Boquillas Flags near Big Bend, different story.  The brown flags capping some of the hills are chock-full-o ammonites and belemnites, best I can tell, somewhat equivalent to the mid to upper Britton fauna of the DFW area.

[jpc]

19 minutes ago, Uncle Siphuncle said:

a sack-o-woe, with net zero personal finds from those flags. 

Can I steal this technical terminology?  I love it.

 

[LSCHNELLE]

Thanks for sharing your experiences.  I remember seeing a recent fossil report of yours on a trip to New Mexico (or West Texas?) with your wife in lieu of the CoVID19-cancelled planned Caribbean vacation. It seems that you hit the Turonian formations and made some nice ammonite finds.  Is that similar fossil hunting to the Boquillas Formation?

[Uncle Siphuncle]

5 minutes ago, jpc said:

Can I steal this technical terminology?  I love it.

 

Hahaha.  With your amount of field time, you have at least the same equity in this phrase as I do.