Texas Trilobite Hunting in Mineral Wells

[GPayton]

Every time I begin a new trip report here on the forum I feel like I need to apologize for how long it's been since my last one. Because although I haven't written anything up since October, I've actually been on more fossil hunting trips in the last few months than in the entirety of last year. This is mostly the result of finally getting a car again back in August after spending the back half of 2021 and almost all of 2022 without one. 

 

In fact, I've made so many trips I haven't actually given myself enough time to write up a report about the last one I've undertaken before I'm back on the road and off on the next. So hopefully this report will be just the first of the five I need to eventually type up. 

 

With that out of the way, let's talk fossils! Specifically Pennsylvanian ones - the second half of the Carboniferous for non-Americans. Last fall I was finally taking my first paleontology course as part of my geology undergraduate degree. It was invertebrate rather than vertebrate paleontology, where most of my interest lies, but it was a paleontology course nonetheless so I had nothing to complain about. I was incredibly excited to take the course, and even more excited when I saw that there was a field trip planned for the middle of October to Mineral Wells, an incredibly popular fossil locality west of Forth Worth that I had only had the chance to visit once before. 

 

As a member of the Dallas Paleontological Society like myself, my professor decided to plan for us to make a brief stop at the DPS-hosted Fossil Mania convention in Glen Rose on our way to Mineral Wells further to the north. It was great getting to catch up with different members and seeing all the incredible fossils on display - especially those that were self-collected elsewhere in Texas. The two that really caught my eye that I just had to take pictures of were two riker mounts of Xiphactinus fossils. I'm obviously a little biased towards this giant Cretaceous fish species as I'm still eagerly awaiting the eventual excavation of one that I found with @Jared C last August. Seeing these displays definitely got me excited for what we might end up digging out! 

 

 

 

Bonus: To the left of the framed Xiphactinus material is the largest plesiosaur vertebra I've ever seen found from the North Sulphur River.

 

While at Fossil Mania I also got to meet another member of the Forum in person: @JamieLynn! I hadn't realized she was a member of the DPS as well, so I was pleasantly surprised to finally meet the woman behind the incredibly well-done identification guides to Texas fossils that I've seen posted here on the Forum before and that she was selling laminated versions of during the convention. It was nice meeting you Jamie! 

 

After leaving Fossil Mania it took us about another hour to get to Mineral Wells and the muddy borrow pit that serves as the fossil park. The last time I had visited was two years earlier and I had always intended to go back - but instead I had been tempted by the possibility of mosasaur bones at the North Sulphur River, which I've visited more times than I can count. 

 

It had just rained in Mineral Wells the day before and the sky was overcast and threatening to rain even more when my class arrived. Fortunately I had brought my creekstomping boots and was well-equipped to trudge through the thick mud that covered the pit. I can't say the same thing for my classmates, however - I saw a lot of shoes go from white to dark brown within the first couple minutes. 

 

The upside of the bad weather though was that we had the whole park to ourselves, and I had the feeling that the rain had probably washed out some good stuff. The last time I had visited the pit was full of other fossil hunters and was bone dry and had been for weeks, explaining why it had been so thoroughly picked over. This time I hoped I might finally find one of my bucket list fossils: my first trilobite. 

 

I knew it was possible to find trilobites here, both from what I've heard other people on the forum say before and from the giant sign that the DPS erected near the entrance to the pit, showing some of the fossils that had been found in the park before. Although I love my prehistoric vertebrates, trilobites have always been at the top of my list of prehistoric animals that I'd like to find, so I was excited to get the chance to look for them again. 

 

Ready to look for the elusive trilobites, I half-skidded my way down the slick slope to the bottom of the pit. The ever-present crinoid columnals that the park is most well-known for covered every inch of the ground. It was impossible to step anywhere without putting my foot down on at least a small handful of them. Having collected far too many of the little round discs on my previous visit I mostly elected to ignore the crinoids unless I saw a large section of them joined together or a rare calyx fragment. Finding a complete calyx with all the arms at the head of the crinoid still attached has long been up there with a full trilobite as one of my bucket list finds. 

 

The first thing that I noticed once in the pit was how much larger the average fossil was compared to the last time I had visited. I chalk that up to the crowds of other fossil hunters not yet having a chance to come out and find them. Huge (by brachiopod standards at least) spiriferids were dotted all over the place. I took pictures of some that had already been broken before I managed to find one that was complete enough to save. 

 

 

 

 

I was able to find a couple of six inch long crinoid columns as well, but unfortunately didn't get any pictures of them. Either way, my attention was quickly drawn to a section of the pit where most of my classmates were gathered up and looking at something held by our class TA. I hurried over and was greeted by the sight of my first Texas trilobite. It was about half the size of the fingernail on my little finger and looked at first like a small white pebble, but the ridged lines that made up the trilobite's body gave it away. For something so small and unassuming it definitely lived up to the hype, and once I had overcome my jealousy I began scouring the mud with renewed excitement. 

 

Before I had gotten more than a couple of steps away, I heard a shout behind me. Our TA had somehow managed to find another trilobite in less than a minute. Even more incredible, this one was larger and fully splayed out unlike the first which was rolled up on itself. Apparently enrolled trilobites are much more common discoveries as when they were alive they would roll up on themselves when threatened, which was often the case when they were buried alive by mudflows on the seafloor. It's also possible that their bodies just naturally curled up after death like some modern insects, but I'm a lot less certain about that. 

 

Shortly after our TA found his second trilobite it was time to leave. Having stopped at Fossil Mania on the way meant that our time spent in Mineral Wells had to be cut down to only an hour. Annoyed that I didn't have a trilobite to show for my efforts, I began walking back up the incline out of the pit to where our vans were parked. But on the way something caught my eye. It was an incredibly thin, ridged fragment of "something." I picked it up and carried it in the palm of my hand back to the parking lot. It wasn't until I had sat down in the car that I got a better look at it. 

 

 

 

 

I couldn't be completely sure at the time, but it definitely looked like part of a trilobite. Specifically a trilo-butt! 

 

 

It was only a fragment, but it was enough to re-energize me. I decided that the following weekend I'd have to make my own solo return trip to spend more time in the park. 

 

That next Saturday I woke up bright and early and loaded up my equipment with coffee in hand. I made a stop in West on the way up, which if anyone is familiar with central Texas they will know as one of the best places in the state to get fresh kolaches. Taking my breakfast to-go I drove the remaining two hours back up to Mineral Wells. 

 

Once again the park was deserted and I was the first person there that morning. As far as I could tell the majority of the mud in the pit was undisturbed except for where my class had walked through it so I had my hopes up high that a more complete trilobite might be in the stars for me that day. And wouldn't you know it, within the first five minutes I had found what I had come for. 

 

 

Not just one trilobite, but several! The enrolled one furthest away from my fingers was what caught my eye, but there was also another fragment of a pygidium from a larger individual directly behind it (which can be seen slightly above and to the left of the enrolled trilobite). And not only that, but when I got home I spotted a third enrolled trilobite encased in the portion of the matrix obscured by my fingers in the photo above, although significantly smaller than the one I first saw. 

 

I believe the majority of trilobites at Mineral Wells are a species of Ditomopyge, with some of the larger and rarer ones being Ameura - I could be totally wrong though! Someone that knows the Texas Pennsylvanian better than I do feel free to correct me. 

 

After taking a couple moments to soak in the satisfaction of finding what I had come for so quickly, I turned my eyes back to the ground and continued my search. It didn't take long before I spotted yet another trilobite. 

 

 

And then another: 

 

 

 

None of the trilobites I found had the cephalon, or head, preserved. At the time I couldn't have cared less, but finding a trilobite from the park with the cepalon and its compound eyes still preserved has become my next goal. 

 

In my frenzy to find trilobites I had let my eyes become unfocused in terms of anything else. Taking a break from the little bugs I looked back over the patches of ground I had already covered to see if I could spot anything else. 

 

Not too far from where I found the first trilobites I saw one of the tell-tale button-like plates from an archaeocidarid urchin.

 

 

As well as a nice little gastropod (probably Pseudozyglopleura - a first for me!).

 

 

The morning wrapped up with a small fragment of a crinoid calyx.

 

 

 

....and one more trilobite for the road!

 

 

 

Of course, already being in the area I couldn't resist the opportunity to visit another famous Texas Pennsylvanian site. But I'll save that for another report....

 

- Graham

Edited April 15, 2023 by GPayton

[Mikrogeophagus]

Cool stuff!  

 

That's a fun experience to get to go on a hunt with your class. I wish one of my profs was in DPS lol.

 

Looking forward to that x-fish finally getting excavated!

[automech]

By your photos, I'm completely amazed at how littered the ground is with fossils.