Tuesday, November 4, 2014

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


  1. Huh! Here on the East Coast, Mosasaurus maximus (=hoffmanni) skeletal fragments are relatively common. I recently just went on a trip for my museum to Ramanessin Brook,NJ, in which fossils from the Upper Campanian are sifted for. Mosasaurus parts can be found here, but alas, none were found by me. I wonder if there is a correlation between the relative scarceness of Mosasaurus material in the west where there is a surplus of tylosaurine mosasaurs. In the Northeast, the only tylosaurine I can think of is Halisaurus, but materi of that taxa is relatively uncommon. I would love to hear your opinion on my tylosaurine/ Mosasaurus arms race idea!

  2. I think a lot of the lack of Mosasaurus remains from Kansas has to do with a two-pronged issue: There is a very small amount of outcrop of post-Sharon Springs aged strata (Weskan through Lake Creek, IIRC, just a few spots in one or two counties) and that literally no one has done much fieldwork out there since about 1930. Never fear though, we have Wally's big brother waiting to be recovered later this spring, and a probable third one was recently identified. Great time for Kansas mosasaurology!

  3. (Sorry for the super late response, as I've been writing a book which is extremely time consuming)

    The model of the skull doesn't look to me like anything really close to what Mosasaurus skull material I've seen. Congratulations on the likely new species you've found!!

    All the best,


  4. For an up close look at the critter, we will have the cast of the skull on display at SVP in Dallas this year.

  5. Any further news on this suspected Mosasaurus, especially the bigger one (RMDRC 14-050)?

  6. We recovered the bigger one in November. Nice articulated tail. I'd estimate it at 90%+ complete. More photos and info once we get Pete III out of the lab and we have time/space to prep it out.