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A fulfilling day in the Texas Eocene (3/17/2024)


Jared C

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For a little while now, @Mikrogeophagus and I have been trying to meet off the forum and hit some spots together. With spring break ending yesterday, we finally found the perfect opportunity before our classes resumed.

Tyler had recently singled out a promising locale for middle Eocene crabs, one that neither he or I had visited. As it later turned out, I had passed by the spot before but never committed to its investigation. I was pleasantly surprised at its serenity, and Tyler and I found easy conversation as we weaved through beds of touch-me-nots and waded through silty waters.

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Our first efforts were concentrated on a small tributary that branched off and reconnected with the main stream. We knew we were looking for concretions, but did not know the nature of them and assumed most would be duds. It was with that attitude that it smacked open my first concretion of the day, decimating a crab inside!

 

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While certainly disappointed, we were both enthusiastic about the find - it meant we were in the right place and we now knew what to watch out for. 

 

Concretions started popping up quickly, sprouting out of the black banks like earthen easter eggs. Many proved fruitful, with a surprising proportion containing the crab Harpactocarinus americanus. At the time, we didn't know the name - content with just the thrill of discovery in a beautiful setting. 

 

We soon discovered some crabs were robust enough to have survived the currents of the stream and could be found in gravel - though just their carapaces. We each claimed one side of the bank and enjoyed success, while occasionally checking the gravel islands between us. 

 

One of my favorite finds was this unsightly avocado shaped concretion, bearing a claw that promises a beautiful specimen inside:

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Displaced carapace found among roots on the river bank:

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Notice the eye holes!

 

Harpactocarinus americanus wasn't the only critter of note at the locale: Giant gastropods were found in unusual proportion compared to the famous Whiskey Bridge locality of equivalent age, but there was a conspicuous lack of shark teeth. Deep into the hunt, Tyler did find two - one irrecoverable blade in a concretion, and a smaller Negaprion(?) to act as the only success on the fossil vertebrate side for the day.

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Soon after, Tyler found a large Belosaepia ungula prong, shown here from its underside. These are uncommon cuttlefishes that had a horn (called the "prong") growing on its backside like a short, stiff upturned tail, a character that can still be seen reduced and vestigial in some modern cuttlefish.  

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The hash around this spot was thick - so choked with shells that it resembled asphalt in some places:

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The site even had a nice sampling of extant fauna - a small Thampnophis proximus (western ribbon snake) could not escape gentle capture, and an alligator gar jaw laid out by recent currents caught my attention. I decided to hang on to it - it may prove a handy reference for general fish anatomy.

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One of the final finds of the day after a long stretch of barren ironstone was another H. americanus, peeking out of hard iron stones and covered by moss. I pulled it away easily, and upon turning it over was met with a beautiful sight:

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Look at that pincher!

 

And so concluded a successful scout with a new friend, right as storm clouds rolled over and the first heavy drops of rain fell. Tyler and I walked back to our cars with an aura of victory, and I gave him another concretion. I'm excited to see the results of his upcoming freeze-thaw cycles. 

 

May y'all enjoy quality preps and fruitful hunts this spring!

Edited by Jared C

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