Actual Mosasaurus from Kansas

Mosasaurs in Kansas, no big deal, there are thousands of specimens known. But what about the actual genus "Mosasaurus"? As recently as 1967, Dale Russell's excellent mosasaur book claimed "Mosasaurus ivoensis" was present in the Niobrara. Since then, Johan Lindgren has moved the holotype of that species (from Sweden) into Tylosaurus. The lone Kansas specimen originally described by Williston in 1902 looks to be attributable (to my eye) to existing known Niobrara mosasaurs, most likely Platecarpus and Clidastes.With the loss of the one possible chalk specimen we're left with a sort of sad thought: Mosasaurus didn't exist in Kansas.

Until now.

Excavating the skull parts

This spring a TPI field crew accompanied by famed Kansas Cretaceous expert Mike Everhart came out to Wallace County in far western Kansas at the request of a private landowner. We were investigating a report of a mosasaur eroding out of the Weskan member of the Pierre Shale, immediately above the much better known Sharon Springs member. Hardly any people work on collecting fossils out of the Weskan, so we were excited for this opportunity in virtually unexplored country. The critter, RMDRC 14-015, got the nickname "Wally" after Wallace County, and was brought back to the lab this spring.

Nice flipper

After recovery and prep it was obvious we were dealing with a pretty darn big mosasaur with a skull about 4 feet long, but what could it be? The only reported specimens this size out of the Pierre in Kansas could be Tylosaurus or Globidens. Prognathodon crassartus from "Eagle Tail, Kansas (now known as Sharon Springs) turned out to just be Plioplatecarpus. the premaxilla lacked a substantial rostrum so that excludes Tylosaurus, though its slight nub of one also excludes Prognathodon (known from other Pierre deposits). The teeth are all sharp and pointy, so not Globidens (yes they are pointy in juvenile Globidens, but with a 4 foot long head, it's silly to consider this critter a juvenile). In the end, with the characters we saw, there was only one logical conclusion.

Bite mark on frontal

Yes Virginia, there really is Mosasaurus in Kansas.

Bulky snout

In fact now there are two: We started recovery of another even larger and more massive specimen from the same ranch at the end of October, RMDRC 14-050. More on that this spring when we return to finish the site. The coolest thing is how the specimens display both advanced and primitive features usually assigned to one or another species of Mosasaurus, but not all in one. It's probably a brand new species, which is really exciting for us.

We are currently restoring and molding the complete skull of RMDRC 14-015 for debut at the Tucson Gem and Mineral show this January, in fact the palate it being installed as I type. The rest of the specimen may take a bit longer to restore, but the world always needs more 30 foot long water lizards. And you can quote me on that.

Newest digsite, mainly concretion

Almost there!

It's down to detailing and painting the restoration on the Explodosaurus. It's starting to look better than I ever thought it would. Hopefully this time next week it'll be safely in a crate and out of sight. If you look closely, the mosa-tisserie has been used for it's fifth skull restoration project. Hopefully more to come.

Explodosaurus gets teeth

Not much progress this week on that cute little Tylosaurus kansasensis, been busy getting the Baryonyx, Steller's sea cow and Minke whale skeletons in their crates and out the door. Next week will be shoehorning the palate in place and hopefully a ton of detailing and painting.

Explodosaurus redux

Just taking an opportunity to update the project before we get buried with snow. Lower jaws are on and positioned, but I still have to finish the braincase and palate.... then on to fixing the whole total lack of teeth problem. Top of skull is 40.5cm long. Such a cute little Tylosaurus.

Explodosaurus reconstruction

Earlier this summer paleo tech Jacob Jett happened upon the exploded out skull of a small Tylosaurus kansasensis specimen in Lane County, KS. I would have found it first, but I was distracted watching a couple of bulls fighting a few hundred feet away while simultaneously noticing the lack of a fenceline between us and them.

Yes, that pile of rubble is the specimen.

It's taken a lot of puzzlework to get the pieces back together, but they are looking better every day. The skull will end up being under 17 inches long when finished. Most bones are still present and I am actually a bit shocked how much of it has fit. Now, how to get the bleached bone to look like the in situ material....

Mosasaur skin prep

Recently Dr. Johan Lindgren of the University of Lund, Sweden visited our lab to look at our mosasaur collection. He has just published a paper with colleagues on soft tissue preservation in the mosasaur Platecarpus from western Kansas, available here. I had noticed some non-descriptive"smears" around the skull of our Tylosaurus nepaeolicus specimen "Tracie" RMDRC 08-002 while preparing it, and thought it warranted further investigation. We removed the specimen temporarily from display and I brought it into the clean room for further preparation. This was important so that I could shut off the lights. Why on earth would I want to do that?

Simple: The phosphatized remains of mosasaur skin will glow under blacklight! They are much more visible than under natural light and it makes preparation easier.

Preparation was fairly difficult, but we may have discovered the first skin preserved from the head region of a Tylosaurus ever. I'm currently writing a paper on the preparation techniques involved, so stay tuned for updates soon!

Fossil of the week 4/13/09

For our inaugural installment I present to you RMDRC 08-002, a Tylosaurus nepaeolicus specimen that was discovered in May of 2008 by John Bennitt in Gove County, KS. Lower jaw length is 757mm, for those of you keeping score. This was found on a private ranch where our company has been scouting for nearly 25 years. Because the Niobrara Chalk erodes so readily, the entire outcrop must be scouted every 2-5 years. In fact, this specimen was discovered less than 100 feet from a tiny Clidastes skull that I found 2 seasons prior.

Since this is an articulated specimen, not much else will be done to it. Taking it apart for a 3-D mount risks too much damage to the skull, and articulated chalk specimens tend to have a lot of distortion from being smashed flat. In any case, there are plenty of cool things about this critter that re already shown. If you look closely at the neural spines of the anterior dorsal vertebrae, you'll notice a nice arc of missing bone. Click on the image for a larger view if jacket 1 of 3. This is a bite mark attributed to the shark Cretoxyrhina mantelli, whose shed teeth were also found lodged in Tracie. There appears to be a little preserved skin in both the left dorsal and lateral temporal openings, and the sclerotic ring of the eye is still in place. The cervical, dorsal and pygal vertebral series are complete, however the limbs and much of the tail appear to have been forcibly removed from the animal, hopefully after it died. This specimen is currently off exhibit due to Darwin and Dinosaurs, however it will return on display in July.