Jump to content

Trip Reports

  • entries
    13
  • comments
    8
  • views
    1,337

A walk in the Austin Chalk (two cidarids!) (4/01/22)


Jared C

191 views

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 :P

 

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:

 

IMG-8001.thumb.jpg.5a1df3c881a9facdac083303245c309f.jpg

 

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. (update: I now know that these are cidarids - funny that on april fools day, I make two of my rarest invertebrate finds, back to back. Odds are I won't have a luckier day in the invertebrate field ever again)

 

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:

IMG-7991.thumb.jpg.fe29b10c3e503cd3ae643f1ba163cce8.jpgIMG-7990.thumb.jpg.390edad83c08e43ca8555affea58a14d.jpgIMG-7988.thumb.jpg.a5283ac47eb4a4b81e31ef86fe546ad7.jpgIMG-7987.thumb.jpg.fb10e6a8373ae1b5390f70033a1aacdd.jpg

 

 

 

 

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!

IMG-7993.thumb.jpg.4f6cb59fc8adf2ecb4849eddd6fd78da.jpgIMG-7995.thumb.jpg.82f313f251b3a255e202d8fa9f9ba45e.jpgIMG-7996.thumb.jpg.cb75110c0b2b37b89b9001ad5e35ae42.jpg

 

 

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

IMG-8002.thumb.jpg.a597413fb5af9cd31e1d090f895d5438.jpg

 

Smaller ammonite below:

IMG-7998.thumb.jpg.fdef5f2236a473dfebbc3a74eaf3ede9.jpg

 

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.

(update: rest assured, I won't be tackling these echinoids with my rudimentary prep skills - It'll be done by a professional)

  • Enjoyed 1

4 Comments


Recommended Comments

DPS Ammonite

Posted (edited)

Once the urchins are prepped, give us a look. There are two good recent books on Texas echinoids. I believe that one or both of the authors are Forum members.

 


Collector's Guide to Texas Cretaceous Echinoids by William Morgan.

Morgan 2016


Fossil Echinoids of Texas: A Monograph of Fossil Sea Urchins by William Thompson 2016

 

 

 

 

 

Edited by DPS Ammonite
Link to comment

I only recommend Morgan's book. 

 

The other has many documented errors and been ignored or discounted by other echinoid researchers.

  • I found this Informative 1
Link to comment
Jared C

Posted

3 hours ago, DPS Ammonite said:

Once the urchins are prepped, give us a look. There are two good recent books on Texas echinoids. I believe that one or both of the authors are Forum members.

 


Collector's Guide to Texas Cretaceous Echinoids by William Morgan.

Morgan 2016


Fossil Echinoids of Texas: A Monograph of Fossil Sea Urchins by William Thompson 2016

 

 

 

 

 

Gotcha, thank you. I'm looking forward to getting these cleaned and actually immersing myself in echinoids, so I'll make at least a few posts/updates about them.

Link to comment
Jared C

Posted

1 hour ago, JohnJ said:

I only recommend Morgan's book. 

 

The other has many documented errors and been ignored or discounted by other echinoid researchers.

Good to know, thank you 

Link to comment
×
×
  • Create New...