Discovering the Kamp Ranch Limestone: Ptychodus Frenzy

[Mikrogeophagus]

This month I decided to take on the challenge of finding my first Kamp Ranch sites. It's not the easiest thing to do since, to my knowledge, the elusive layer is not mapped anywhere. I spent a lot of time scouring the waterways of North Texas and by the end, I came up with two distant potential spots for a couple days worth of hunting.

 

I traveled to the first site one sunny morning and after a long walk, I finally made it to the water's edge where I met endless limestone slabs filled with Collignoniceras woollgari impressions, meaning I was just in the right place. I readied my rock hammer and began the search. It was mostly just oyster fragments initially, but soon enough I started picking some nice Squalicorax and tiny Ptychodus anonymous. The Kamp Ranch was pretty hard, and that meant that the Squalicorax rarely survived extraction. Even the Ptychodus, which are usually quite resilient, ended up shattering more than I'd like to admit. I built up a steady flow of Ptychodus anonymous before spotting an enigmatic crusher tooth. I was excited since it appeared to be very large and of a rare species, but it turned out only to be a fragment. What's strange about it is the flat crown and few yet thick transverse ridges on top. The only species I know of this nature is Ptychodus latissimus, but in Texas those are better known to begin in the Basal Atco (Early Coniacian). I did some research at home and found that P. latissimus has been observed in Middle Turonian outside of Texas, so I suppose it is a possibility here.

 

Possible Ptychodus latissimus

 

After some more finds like a huge Xiphactinus tooth and Cretoxyrhina cusp, I at last flipped the slab that would yield the definitive best find of the day. In perfect condition was the biggest Ptychodus anonymous I had laid eyes on. I was familiar with the fact that the Turonian P. anonymous morphotype was supposed to be larger, but it's always different seeing it in person. Initially, I wasn't totally sure if it was P. marginalis instead, but the taller crown and anonymous-esque marginal area led me to believe it was the former.

 

P. anonymous

 

A couple weeks later, I ventured out to my second site. This locality had a smaller exposure on timid waters, so I was looking forward to being able to hunt for freshly eroding fossil from the limestone wall. When I first showed up, I was once again greeted with limestone slabs containing Collignoniceras woollgari impressions, however I was struggling to even find a single shark tooth among them. I recalled reading in the past that the Kamp Ranch can be spotty, so the possibility that this locality might be barren was looming in my head as I traversed the creek.

 

Once I reached the exposure, I pulled out the probe and danced my way through the limestone blocks. I skimmed through the whole exposure pretty quickly, but only came out with a few Squalicorax teeth and a big Cretoxyrhina from the gravel. I was a bit disheartened. This was such a nice looking location, how could that be all there was to offer?

 

Cretoxyrhina mantelli in the gravel

 

Desperate to salvage the day, I got down low and searched the under side of the lowest slabs. After dodging a spider, I spotted the outline of a Ptychodus sticking out from a shaley layer cemented to the underside of the limestone. The matrix was soft enough I could dig it out with my fingers. Then I noticed another... and another. This layer was extremely productive and soon I pried off a slab of it to process atop a boulder. I could not believe the number of teeth I was finding. 

 

Pristine teeth from just ONE slab

 

Not only were the Ptychodus numerous, they were also diverse. Shawn Hamm in a recent paper listed six species of Ptychodus occurring in the Kamp Ranch. I didn't know it at the time, but after some cleaning, I have EVERY one of those species represented from only a day's worth of hunting! Some of the more special ones included P. mammillaris which was a new species for me. Also, I found an upper medial file tooth of P. marginalis(?) which are always a neat tooth position with their unique proportions. P. decurrens is one I usually don't associate with the Turonian in Texas, but they made it through and I managed to snag a textbook one.

 

Ptychodus mammillaris

 

Upper medial file Ptychodus marginalis(?)

 

Ptychodus decurrens 

 

The Lamniformes were also plentiful, though difficult to bust out in one piece.

 

Dallasiella willistoni, a common smaller tooth from the Turonian

 

Huge Cretoxyrhina mantelli

 

One of the coolest finds was not a tooth at all or even from a vertebrate for that matter. The Kamp Ranch is a bit famous its fossil pearls. When I spotted a perfectly spherical curvature from the slab I put in 110% effort to pop it out cleanly and not have it fly away into the flowing water below. It came out in one piece and after looking through the microscope, it has the polygonal structure expected for a Kamp Ranch pearl.

 

Inoceramid Pearl. That rock it came from also had two Ptychodus anonymous and a Cretoxyrhina mantelli as well

 

Towards the end of my slab-splitting, I found an enigmatic fossil. Its flat and a fishy bone look with a bunch of holes on one side. The other side is completely smooth. My best guess is it's from a Plethodid fish, but it looks pretty different from the South Bosque (also Turonian) Plethodid fragments I have in my collection.

 

Possible Plethodid

 

After a long and rewarding day hitting the slabs, I turned around to head for the car. Of course, my eyes were locked on the gravel anything I had missed on the way in. No teeth were to be had, but I did find a thin shale ammonite entirely separate from matrix. I have no idea how it managed to survive in the gravel. It's so delicate and even has the tubercles of the shell intact on both sides. It's obviously not from the limestone, but would this still be Collignoniceras woollgari? 

 

 

 

It was a great day. I'll be visiting both of these sites again in the future for sure!

 

Finds at the second site:

 

Top L to R: P. marginalis, P. mammillaris, and Undescribed species

Bottom L to R: P. anonymous, P. whipplei, and P. decurrens

 

Top: Cretoxyrhina mantelli

Bottom L to R: Plethodid?, Dallasiella willistoni, Inoceramid Pearl, Cretalamna sp., and Squalicorax sp.

 

Thanks for reading!

[Jared C]

32 minutes ago, EPIKLULSXDDDDD said:

Dallasiella willistoni, a common smaller tooth from the Turonian

 

I've somehow never heard of this genus, what a wonderful surprise to encounter. Time to go off on a rabbit hole

[Mikrogeophagus]

6 minutes ago, Jared C said:

I've somehow never heard of this genus, what a wonderful surprise to encounter. Time to go off on a rabbit hole

I came across a handful in my South Bosque matrix, but they are easy to overlook. Keep an eye out!

[LSCHNELLE]

@EPIKLULSXDDDDD

Maybe you could post your upper medial file tooth to the tail end of the Ptychodus ID section. I think it's a much better example of a UMF Ptychodus marginalis than my pictured one.

Edited April 24, 2023 by LSCHNELLE
Typo

[Mikrogeophagus]

35 minutes ago, LSCHNELLE said:

Maybe you could post your upper medial file tooth to the tail end of the Ptychodus ID section.

I'll go ahead and do that. Bout time I contributed something given how many times I've read through it!

[JamieLynn]

that PEARL!!!!

[ThePhysicist]

Just absolutely wicked 

I do hope you collected some matrix to process for microfossils!

[Mikrogeophagus]

@ThePhysicist I brought home a little baggie of the rich shaley matrix I can break with hands and water to test things out. Just in processing it today I've got a denticle and some teeth! We'll see what the screen turns up soon. Next trip out there I might take a few bigger bags.