Tuesday, March 22, 2011

Jonesing for mosasaurs

It's starting to feel a lot like springtime, which for us usually means trips to western Kansas to our Niobrara chalk localities. We haven't made it out yet (still waiting on that first downpour to wash the winter fluff off of the rocks... it may be a while with this drought) so instead I'll write a bit about a mosasaur that is near and dear to me.
Starting the hole

RMDRC 06-009 "Cap'n Chuck" was the first mosasaur I ever found. It's a specimen of Platecarpus "ictericus" (sorry Takuya, haven't made the species switch yet) from the upper chalk of Logan County, about 83 million years old. I spotted a single dorsal vertebra sticking out of a vertical gully wall, about 12 feet above the gully bottom. Don't ask what I was doing looking up there. My boss, Mike, loaded Jacob and I into the bucket of the bobcat and lifted us up to see if there was anything else there besides the single vertebra. Yep! we discovered the back of the skull, but since it was late October and in the low 50s (with drizzle coming in and lots of wind) we decided to secure the site till the next spring.

In April of 2007 we returned, with a fancy new mini jackhammer that Mike had bought over the winter. Holy moly that thing saved us a lot of time.

We made this big of a hole in 3 days

Do you see the skull?
It turns out field mapping in the chalk is kind of a tough thing to do. The chalk gets all over everything and generally makes life miserable. It's best to save it for the lab. The skeleton was preserved very well, missing the end of the tail. Quick measurements of elements give us a total length of about 23 feet, which is pretty dang big for a Platecarpus.
Main jacket flipped and prepared. Things are much easier to see.

Once show-prepped in the lab it was decided that Cap'n Chuck was complete enough to restore in 3d (most exploded skulls are good candidates, there's less crushing distortion). That meant pulling every individual bone out of the jacket and cleaning it completely. This enabled us to get a good look at some rare parts like the interclavicle and ear cartilages. Hopefully we'll be able to start restoration sooner or later!

Laid back


  1. Great fossil, great pics - thanks!

  2. Thanks so much for sharing these pictures. What a beautiful specimen. After so much hard work, you all should be very proud.