Lower Campanian (Austin Chalk)

Texas

lower Campanian

Texas (upper Austin chalk)

Campanian (Pflugerville member of the Austin Chalk)

Texas

This is a taxon famous from the red beds in the NSR, but I've been lucky to enjoy finding these hundreds of miles away in the Austin Chalk, stratigraphically below the Ozan red beds that are so famous for them.

Campanian (Ozan fm)

Texas

I'm not the best with tooth ID's, since most of the mosasaur teeth I've seen in person come from basal Plioplatecarpines, whose teeth are mostly indistinguishable. But, realizing this broken apex from a much larger tooth lacked fine striations and had a faint anastomosing texture made me suspect a mosasaurine origin, as opposed to the most common large mosasaur from the Ozan - Tylosaurus proriger. @pachy-pleuro-whatnot-odon was kind enough to walk me through the ID points and converged on indeterminate Prognathodon sp., and paleontologist Mike Polcyn gave the same opinion. Prognathodon is not described from the Ozan formation, making this an exciting find. There seems to be an elusive giant still lurking Texas's most iconic formation.

Campanian (Ozan fm)

Texas

An uncommon genus for me to encounter, it was a pleasant surprise to see a Campanian example of the taxon.

Campanian

Texas

These two caudal vertebrae, found in the same stream, demonstrate some of the size variation seen in mosasaurs. Notice the two pits of the bottom vert - those are for the haemal arches, and with no other bony attachments except for the base of the neural spine (on the other side), we can infer that this vert came from close to the end of the tail, probably putting its owner in the 30+ foot range. Alternatively, though very worn, it seems that the smaller vert came from a position closer to the pelvis (though still caudal). Likely from a juvenile of what had to already have been a different, very small species. 

The teeth are not diagnostic to species, and current unpublished research has questions about the validity of certain species within the genus - not my place to discuss openly just yet

Though I used to have this in my Santonian album, closer investigation of the geology of the site has led to a pretty conclusive lower Campanian age. Close the the Austin Chalk/ Ozan boundary

Lowermost Campanian

TX

This Cidarid seems to have affinities with Stereocidaris sceptrifera from the late Cretaceous of Europe, but the geographic separation and lack of literature on this new world form suggest a potential undescribed species of Stereocidarid. This is the same taxon as the other Cidarid in this album - both were found the same day, at the same locality  

Notice the partial aristotle's lantern (mouth), as well as a few of the short, flattened scrobicular spines (which protect the muscles of each primary spine) attached near the bottom. Though crushed, this specimen is excellent. 

Huge thanks to @JohnJ for the excellent photos, and both John and @Ptychodus04 for the prep

Discovered April 1, 2022

Lowermost Campanian

TX

This Cidarid seems to have affinities with Stereocidaris sceptrifera from the late Cretaceous of Europe, but the geographic separation and lack of literature on this new world form suggest a potential undescribed species of Stereocidarid. Huge thanks to @JohnJ for the ID tips and excellent photos and @Ptychodus04 for the prep.

Discovered April 1, 2022

Campanian

Texas

Ozan fm Tylosaur tooth found in gravel. I'm of the opinion that perhaps the assignment of T. proriger to the Ozan Tylosaurs is hasty - though it's difficult since the obvious differences between these and the holotype are restricted to a single cranial element. Not sure I should say much more on that - while it's not an existing research question it's not my original observation.