A Little Magic Left in the Fossil World

[Mikrogeophagus]

Fairly recently, I crossed the first year anniversary of my time down here in South Texas. Despite the difficulty of searching this region, I've had the pleasure of experiencing a ton of strange new formations and gaining fresh perspectives on the ones that I thought I'd already understood. In my second school year, I've continued reserving time for expeditions, in hopes of collecting new specimens or at least enjoying a hike through some scenic Texas geology (of which I've had too many ).

 

Early Sunday morning, I woke up to my alarm for a hunt I'd been planning all week. Unfortunately, the weight of last weeks tests and lab assignments kept me pinned beneath the sheets, helpless to overcome the fatigue. In addition to physical constraints, my brain was also very outspoken. The triple digit forecasts and long drive made the prospect of shutting the blinds for another lazy Sunday very appealing. After a prolonged internal conflict ensued, I at last rolled out of bed, emboldened by the knowledge that a free weekend like this may not be all that common pretty soon. Albeit a little behind on schedule, the engine was quickly fired and all four wheels were rolling on a westward route to a novel frontier.

 

It was already well into the day when I pulled into my first locality. Upon exiting the car, humidity instantly fogged my glasses. Things were rather quiet and the only souls out and about were small packs of stray dogs (who were thankfully uninterested in me). From atop the hill I could see the border wall and Mexico stretching far beyond.

 

 

I am well aware that there are about a million reasons one cannot/should not fossil hunt in Mexico, but I can't be the only one daydreaming of what might lie beyond. It's strange to know that the geology simply continues unimpeded underground for miles and miles, meanwhile I am stopped at a hard barrier. Despite being within only a short walk away, somehow it feels like I am gazing into an untouchable alternate universe... if that makes any sense.

 

The fossils at this spot were sadly underwhelming. Although I managed to find a decently thick oyster bed, I couldn't locate any of the more intriguing invertebrates, let alone shark teeth. So I moved on.

 

I then drove through a small construction site. The terrain was uninteresting, but a drive-by scouting of the ground yielded a chunk of Sphenodiscus, a personal first.

 

Sphenodiscus sp.

 

The next spot was a huge expanse with many different layers of Escondido Formation exposed. I was very excited on the walk from the car, but it was quickly apparent that the fossils were still rather sparse, despite the promising initial appearance. That same oyster bed from earlier kept turning up again and again without any success. After a half hour trek, I finally noticed a subtle faunal change. Instead of just oysters I began spotting numerous gastropods and some scallops.

 

Two gastropods from the Escondido

 

The fossil hunter within me took this as a sign to begin a more thorough search and at long last I was simultaneously rewarded and cursed with shark material. A vertebra and two decent teeth were wedged into some extremely resistant sandstone rocks. The vertebra I didn't bother with because it would inevitably turn into a pile of dust before it came loose. The smaller shark tooth, a Carchias sp., popped out easily with a few swings. The bigger tooth, a Cretalamna maroccana, was my main target and proved far more difficult.

 

Shark vert

 

Carcharias sp.

 

Cretalamna maroccana and typical Escondido oysters

 

Every swing on the C. maroccana reverberated soundly throughout the clear sky with a metallic clang. Even with the most effective strikes, only minute specks of rock were ejected from the contact point. I wish I was exaggerating, but it took about an hour to create a zone of cleared matrix around the tooth. Somewhere along the way I thoroughly convinced myself that to get this out in one piece alone would be enough to justify the hardships of the day. Outside of my mind, the temperature had begun to peak at 100F (which somehow feels way hotter on the border!). Each move shook a drop of salty sweat into my eyes. My arms began to glisten and every time I took a breather, I'd accidently brush my skin against the burning metal of the hammer.

 

I made the final impact to free the tooth from its almost insurmountable prison. It responded by leaping many feet into the air and nearly escaping my sight. When I retrieved the specimen to fully enjoy the fruits of my labor, I instead found that the efforts did not completely translate. By now I was wishing I had taken my B plan and sifted sands off Port Aransas...

 

Busted up C. maroccana

 

And with that disappointment, I set out for one last site. It was an inconspicuous spot and is perhaps the best hidden locality I've logged so far. After a walk, I got down and began some cursory searching with low expectations given the unrewarding hours already burned. This spot, though, seemed to offer something different. Besides the typical Escondido sandstones, I came across a very strange grey/green shale. A closer look at one block with an orange splotch awakened me from my exhausted mood. The first sign of crustacean material!

 

 

An unmistakable crab carapace

 

The newfound adrenaline prompted me to go into a frenzy and soon I was seeing orange splotches everywhere. Most were seemingly only mineral stains, but some were crustacean claws. However, only a couple minutes of looking brought me to the ultimate prize and made me wonder if I had begun some hallucinatory stage of heat stroke. Never before had I seen such a crab from Texas.

 

 

Costacopluma mexicana

 

There it was clear as day: An ornamented carapace and some attached limbs. Very carefully, I transferred the specimen to its own bag. The dryness and fragile nature of the shale made disaster never quite far enough away. I quickly collected more crab carapaces, but none could have compared. Now it was certain that the trip was well worth it. Some cleaning at home helped bring out the full beauty and gave key information on ID.

 

Costacopluma mexicana

 

C. mexicana

 

C. mexicana

 

C. mexicana

 

Costacopluma mexicana is a species of crab only known (to my knowledge) from the Maastrichtian of NE Mexico. Being so close to the border, it seems that I didn't need to daydream in order to experience the thrills of diving into their wonderful/alien fauna. This zone of crustaceans was also something I could not find info on in the literature. At times it can feel like too much of the Texas geological record has been thoroughly described and each fossil is never really much of a surprise given what's already documented. Special moments like this, however, remind me that there is still some magic left to the hunt. With time and patience, any one of us can be the first to dissect a snippet of the ancient past and see the world from a new vantage point.

 

Some other interesting things included a fish scale and a possible leaf. 

 

Fish scale, ?leaf, and disarticulated claw

 

The site was small, so I made quick work of searching it. One day, when the temperatures are much more hospitable, I will have to make a return. I feel like there could be a lot more to discover and, until then, I will likely spend many hours pondering on the prospect instead of sleeping. 

 

I have way too many fossil ideas, plans, and goals to keep up with, so look forward to my future reporting from some other random parts of the state.

 

And to all who are reading this, thank you, I hope you have fossil sites keeping you up at night as well .

 

 

[TqB]

A very enjoyable read with my morning coffee in chilly England, thank you!

Edited August 20 by TqB

[Fossildude19]

Great report, and finds. Well written and engaging!

Thanks for the vicarious adventure.

[JamieLynn]

wow! Congrats on that crab! 

[Jaybot]

Thank you for sharing!  What a nice crab

[JohnJ]

Thanks for posting, Tyler!  

[Jared C]

This gave me the motivation to finally finish up my own trip report backlog. You are an excellent writer

[Mikrogeophagus]

1 hour ago, Jared C said:

This gave me the motivation to finally finish up my own trip report backlog

I am equally excited and terrified to see what you've collected from your recent trip. Get that report done quick! 

[FossilDAWG]

So well written I almost felt as if I was there.  Unfortunately when I looked I was totally unable to find any of those excellent crabs on my prep bench.

 

Don

[deutscheben]

Thanks for the excellent report and congratulations on the finds! That definitely looks like a fish scale to me as well. 

[MB]

Bravo !!! Love Costacopluma