Discovering the unexpected in the Texas Turonian

[Jared C]

Perhaps the most definitive, lasting project I've had during my short time in paleo is the excavation and study of a basal mosasaur skeleton my step brother and I found in September of 2021 (If you missed it, it's in my blogs on my profile). The site is on a fairly inconspicuous outcrop of the Eagle Ford formation, in a zone that's atypical for the upper eagle ford, as the rock itself is very condensed compared to what is usual for the upper kef. Notably, while Mosasaur material is very, very rare in the kef (kef is an abbreviation for the Eagle Ford formation), it pokes out with greater frequency here - I have found two other Isolated Mosasaur teeth there before. 

 

Both @LSCHNELLE, a geologist who is very familiar with the Eagle Ford, and a paleontologist that I'm working with have made this observation about this atypical site. Between the three of us, we weren't sure there was another exposure like it elsewhere. 

 

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Over spring break, I was in need of some good luck (after losing the transmission in my new car ), so, finding myself back using my parents car, I made a drive to spot I had scouted a year ago, expecting to see the massively steep Ozan exposure I had spotted from a distance before. 

 

Upon arrival, I was greeted with those gorgeous grey shales in all their glory. Upon closer inspection though, I was surprised to realize that things weren't as they seemed.

The shales were lighter than the Ozan, and physically much harder. I was suppressing exciting pangs of recognition for a few seconds, but it soon became very clear that this massive vertical exposure was an outcrop of that same lithologically atypical zone of the Eagle Ford that produced our Mosasaur. What's more, this site is many miles away, and mapped as a completely different geologic group. It appears that through upfaulting, a cross section of this zone shot through the layers of earth above it, standing as an Island of the Turonian in a sea of much younger rocks. 

 

One feature of the Eagle Ford (or any formation for that matter) is that the bulk of the rock is barren, only interrupted by small intervals of great fossiliferous accumulation. This stood to be true at this site as well, so I set about chasing those shelly lenses that caught my eye and changed my path of life over a year ago.

 

It didn't take long before I came to a shell lens a couple inches thick. One con of this site being a vertical cliff is that I can't peel slabs up as I can at its sister site, so I had to slowly chip into the lens, one piece at a time. Here are some finds that resulted:

 

Small shark vertebra

 

 

Fish vertebra

 

An oddity, insitu in the middle of the shelly lens. Try your guess first

 

 

 

 

 

Upon removal:

A really lovely Ptychodus tooth that I suspect is the unpublished species also found at our mosasaur site. Since the species has not been described yet, I can't fairly quote any exact morphological features to cement my ID, but I've seen enough by now to "know the look", and have had several of these teeth confirmed by Shawn Hamm. This tooth was one of the best fossils I could find to confirm the comparison to the atypical kef mosasaur site. 

 

Here's another view:

 

 

Shortly after, I distracted myself from hammering out small chunks of the lens and took a peak under the one tiny 3D protrusion of the lens that there was. Under a ledge only a few inches wide sat a fossil that made my heart skip a beat:

 

 

The tip had fallen off, likely from hammer vibrations since I chiseling not far away. But, undeterred, I extracted the slab and was met with an imperfect, though still beautiful sight.

 

To find a mosasaur tooth after removing what was in total less than a gallon bag of slabs made for an exciting day. Though broken, a basal mosasaur is a basal mosasaur, who can complain? I was especially excited that this lightning fast find came from a new site - meaning there might just be what I'll happily nickname a "Kef mosasaur lens" that transcends beyond the boundaries of our original site. Any trip where you walk away pondering those things is a good one   

 

Edited March 25 by Jared C
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[Ludwigia]

Fascinating. I'm quite amateurish when it comes to Texan Turonian stratigraphy. Can you please explain to me what "kef" signifies?

[DPS Ammonite]

K = Cretaceous ef = Eagle Ford Group/Formation

 

If you click on Kef NW of Dallas on this Texas Geology map, it will tell you what the symbols/abbreviations stand for.

 

https://txpub.usgs.gov/txgeology/

 

A suggestion to posters; spell out abbreviations on their first use in a post. Then you can use the abbreviation later. 

Edited March 25 by DPS Ammonite

[Ludwigia]

1 hour ago, DPS Ammonite said:

A suggestion to posters; spell out abbreviations on their first use in a post. Then you can use the abbreviation later.

A very good suggestion. Interesting that the "K" is drawn from the German language (Kreide), but is internationally recognized as the correct abbreviation. If I posted OMM, only a few Europeans might just know that it stands for Obere-Meeresmolasse Formation. Otherwise the rest of the world would probably draw a blank.

[FossilNerd]

Awesome report as always Jared! Congrats on the new found exposure and good luck in your new Mosasaur hunting grounds! 

[pachy-pleuro-whatnot-odon]

1 hour ago, Ludwigia said:

A very good suggestion. Interesting that the "K" is drawn from the German language (Kreide), but is internationally recognized as the correct abbreviation. If I posted OMM, only a few Europeans might just know that it stands for Obere-Meeresmolasse Formation. Otherwise the rest of the world would probably draw a blank.

 

I actually looked into this a bit just now, as I did find it rather surprising for the Cretaceous to be named in German - past its obvious of distinguishing the Cretaceous "K" from carboniferous "C" - since so many of the earliest funds of significance were made in Dutch-speaking territory. And, in fact, after having looked at this, I still wonder and haven't been able to clear up whether the origin of the "K" comes from German "Kreide" or Dutch "Krijt" - very similar words, of course, for deriving from closely related languages from the Germanic family...

 

Much seems to hinge on Jean-Baptiste-Julien d'Omalius d'Halloy, born in 1783 in Luik/Liège, which then belonged to the County of Flanders in the Austrian Netherlands (now Belgium). Due to the county's independent status, the local language spoken would've been Flemmish/Dutch, although the official state language would likely have been German. The term Cretaceous was first coined when D'Omalius d'Halloy studied sediments in the Paris Basin, and is, of course, named for the Latin "creta", "chalk", with D'Omalius d'Halloy assigning it the "K" abbreviation. So unless there's a clear statement as to whether he intended from it to refer to either the Dutch or German language, or which language he was more prone on speaking (which, as a nobleman would, admittedly, more likely have been German) I guess it'll remain speculation as to which language version the abbreviation actually came from...

 

Quite the interesting history 

 

 

Spectacular finds, by the way, Jared! Love that basal mosasaur tooth! But that ptychodus is also very, very cool!

[PaleoPastels]

Always excited to read a trip report from you! You’re pretty fluent reading your geological formations- a particular talent Ive noticed in you. I always end up learning a lot from your reports, someday you’re seriously going to be a great teacher and researcher.   As soon as I get my car I can’t wait to explore more of Texas too and learn! 

 

That ptychodus is very peculiar indeed! What a spectacular find. Definitely check out Hamm’s thesis if you haven’t already. A shame the apex is missing from that mosasaur tooth but I agree- mosasaur tooth is a mosasaur tooth! It looks a lot like in size and shape to the one I found around New Years, also Turonian. (Ive been wanting to get touch with SMU staff to find out more about it!) 
 

Always wishing you the best on your mosasaur project! I can’t wait when the species is identified and see your name on a shiny plaque when its museum-ready someday. It’s very inspiring! September 2021 you say? Interesting. 

[JohnJ]

The mystery Ptychodus saga continues....

[LSCHNELLE]

Nice finds! Congrats! Always fun to find a new location. Now, you are using the paleontology to help inform you of the geologic formations and specific  stage! This is something that Shawn Hamm thought should be possible with Ptychodus species just like ammonites, forams, and inoceramids can be used. I think you have got it right on the Ptychodus ID.

[EPIKLULSXDDDDD]

If I had found that tooth I would have totally thought I had discovered the first Middle Campanian ptychodus . Great detective work and congrats on the new Turonian honey hole!

[LSCHNELLE]

@Jared C When you get a chance , please clean off the Ptychodus just a little more and post a few more pics, so you can double check its ID.

[Jared C]

57 minutes ago, LSCHNELLE said:

@Jared C When you get a chance , please clean off the Ptychodus just a little more and post a few more pics, so you can double check its ID.

Will do! I'll put them here

[Jared C]

5 hours ago, JohnJ said:

The mystery Ptychodus saga continues....

 

The apprehension is killing me! Lee and I have been on the edge of our seats waiting for Hamm to publish it for ages 

[LSCHNELLE]

23 hours ago, Jared C said:

The apprehension is killing me! Lee and I have been on the edge of our seats waiting for Hamm to publish it for ages 

Shawn texted me that he has written his part and is waiting on his co-author to complete reviewing the draft professional paper. So, it's out of his hands at this point.

[Jared C]

Here are some more views of the tooth:

 

[LSCHNELLE]

Thanks @Jared C for the better pics.  I am inclined to think this is an L2 or L3 file from the new Ptychodus species rather than a Ptychodus mortini or P. rugosus.  P. mortini often has a crown with ridges radiating outward in all four directions more symmetrically.  This one has more anterior/posterior-orientated radiating ridge symmetry (like P. atcoensis).  The top is a little worn, so I can't see how the ridges join together.  But, it looks similar to the ones Shawn has ID'd for me.  The only exception is that the marginal area on the teeth I found was more fine-grained and circular around the crown than yours.  But, that happens in different Ptychodus anonymous also, so I don't think that is a reason to change the ID.  Some ridges on the new species might cross parallel to the tooth width, but yours does not have that feature.  I don't think that is a deal breaker.  P. rugosus ridges don't radiate in the same manner as this tooth.  So, that eliminates P. rugosus.