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



Tuesday, October 7, 2014

Daspletosaurus reconstruction progressing: Pete III

You know, I think I'm just going to share some pictures as an update to my last blog post. We'll keep the reading part short and sweet. Restoration is coming along well. The skull is up next, and in the meantime we have the leg finished and the arms almost there. Lots more to come over the next few months. It's always good to have new tyrannosaur stuff to play with.

Pete III's scaps and arms

The scapulae were remarkably well preserved in 3D

Left leg before paint

After paint, left leg from the rear

Side view, the leg is HUGE!


Thursday, September 4, 2014

Pete III makes progress: Molding a Daspletosaurus

It's been a long time, not only since I updated the blog, but since we've had any news about our big Daspletosaurus specimen that we dug up in 2006. Well, that's changing now.

Original and prototyped bones
This is basically an update on a post from a few months back where I covered the scanning and printing process if the leg. To get the project moving along we picked some of the low hanging fruit: finishing the left leg! Since this leg was almost complete (missing just one phalanx and strangely, metatarsal III) the restoration was pretty straightforward, comprising of just crack filling. The digits were molded in gang molds and we produced a mighty fine block of metatarsals II through IV.
Original leg ready to mold

That block as well as the long bones were molded so that they can be loaded onto our spin casting machine, enabling us to make high-fidelity hollow casts (saves a lot of weight) that we later fill with urethane foam for durability.

Cast copy of the left pes ready for assembly.
This leg should be ready for display in about 10 days, so don't forget to come by the museum to check it out.

Thursday, July 31, 2014

Platecarpus restoration complete! All hail Cap'n Chuck!

After 8 long years of work, our Platecarpus tympaniticus specimen RMDRC 06-009 "Cap'n Chuck" is finally finished! These last few weeks of the project had been dedicated to finishing the details of the armature as well as packing it for its trip to its new museum forever home. It seems like just yesterday when I was lifted in a freezing drizzle in a Bobcat excavator bucket one October day to investigate a lonely vertebra poking out of the side of a gully wall. Poking around revealed what looked like the rear of a skull, and we decided to come back the following spring to finish the job.
Working on turning a vertical surface into a flat surface

By the time we completed the excavation, we could walk down the debris pile to the gully bottom. We took out multiple jackets since the bone density was so high, working on them in the lab was much safer for the specimen.

Main body and skull block in the Show Prep stage
Once "show prepped" (preparing the jackets to show what is inside of them) we disassembled them and placed the bones in drawers in the Clean Room for safe keeping. There it stayed for years until a customer was found.

Coming together. The white bleached bone 4th from the left is the first bone found
Earlier this year we started restoring the bones for mounting. While we had the bones handy, Cap'n Chuck was molded so copies can be sent to other museums in the future. The mosasaur was incredibly undistorted, the ribs were even round in cross section, unlike the typical Kansas condition of being squished pancake flat.

Dillon (left) vs. Cap'n Chuck (right)


Snakey!
The final result is pretty spectacular. The undistorted ribs helped us get a very accurately shaped torso, with cartilage and even an interclavicle. The skull is beefy and bulldog-like, much different than the lower chalk specimens of Plesioplatecarpus planifrons.
Showing off the pterygoid teeth

Paddle and chest detail
Vertebrae are much larger and more robust than the lower chalk specimens. Surprisingly, the finished mosasaur was a bit shorter in length than we had anticipated, coming in at just over 17 feet (5m) long.



Skull detail



Sunday, June 22, 2014

Beefy Platecarpus Restoration Update!

For the past few weeks, TPI field crews have been scouring the outcrops of Western Kansas and finding some spectacular specimens. More on those in a future blog update.

Since the field crew was gone, the lab crew is much less distracted and has made great progress in assembling the Cap'n Chuck specimen of Platecarpus tympaniticus. Skull reconstruction is now complete and painting of the small restored areas is all that;s left. total length ended up being 52cm, but the width gives it more of a bulldog appearance than the lower chalk Plesioplatecarpus planifrons. I'm still trying to get used to all these new names since the reclassification of plioplatecarpines a few years back.

Top view
The only bones I was completely missing were both squamosals, but they were pretty simple to fabricate.
If you look carefully, we even included the mounted epipterygoids
The skeleton has had individual clips fabricated to hold each bone securely in place. Those subassemblies are now being fastened to the armature. The specimen is intended to be hung at its future museum home, however building it on cables in the lab is too unsteady. The posts supporting the superstructure will later be removed before shipment. The light colored vertebra fourth from the left is the first part of the mosasaur I discovered coming out of the outcrop.
Ribs beginning to be fit, though all still need adjustment

Individual bones are assembled into segments so that it can be quickly and precisely set up in a new facility. All limbs are removable, as are the ribs and skull. The vertebral column breaks down into segments. With any luck though, the steel armature will be nearly invisible on the final mount.

Front paddles nearly assembled.

Thursday, May 1, 2014

Cap'n Chuck Rises: A Teaser

Like many places, progress on various projects here ebbs and flows. Sadly, the Pete III Daspletosaurus restoration project has been temporarily put on hold so we can address more pressing matters. In this case, it's Cap'n Chuck (RMDRC 06-009), a fairly complete and extremely well preserved Platecarpus tympaniticus specimen that I discovered one cold October day in 2006. A recap of the early part of the project can be found by clicking here. Once prepared the specimen sat in drawers in my office for years.
Squalicorax bites on the top of the skull

That's a nice set of ribs
Recently the powers that be have decided that we should restore and mold the skeleton to replace the smaller Platecarpus planifrons skeleton in our cast catalog. Comparing it to the lower chalk mosasaur, Cap'n Chuck has a nearly identical skull length, more gracile lower jaws and wider top of the skull, however its postcranial skeleton is radically different in proportions. Humerei and vertebrae are nearly twice as big. The ribs are surprisingly uncrushed, preserving their original round cross section as well as curvature. In fact they are so well preserved we can even with some degree of certainty determine which ones belong on the left or right side (nearly imossible to do on typically crushed ribs).

Lower jaws, slender and displaying symmetrical tooth replacement
Nearly complete axis showing beefiness


The differences really are amazing. A few years back, Takuya Konishi split Platecarpus planifrons into its own genus: Plesioplatecarpus. I was very skeptical of this split for a long while, but now after comparing the low chalk mosasaur against its upper chalk relative, I'm really beginning to see his point.

Wednesday, April 9, 2014

Scanning a Daspletosaurus

So we all know that fossil skeletons are rarely found 100% intact. This is especially true for larger animals for a number of reasons, from scavenging to paleoerosion to roots to modern weathering. Even with the mighty tyrannosaurs this is true: Sue? Missing bits. Ivan? even less complete. Sir William? The dozens of shed tyrannosaur teeth at the site might be a hint where lots of the parts went. Yum.
Field map of quarry

Quarry during dig



During excavation of Pete III, the TPI field crews kept careful records to document the site properly (as all paleontologists should, I don't care if you're academic or commercial). As we excavated and uncovered bones, they were assigned field inventory numbers, recorded and were mapped to scale. It quickly became apparent that there were only enough leg elements for one. The other one was gone, but where did it end up?

Ankle bone mirrored in the computer
Microstratigraphy along with the mapping provided a possible answer. The sediment indicated that Pete III was located in a crevasse splay deposit. These deposits are formed when a natural levee breaks, squirting water and sediment over the adjacent floodplain. It's like a geological zit. This particular rupture apparently contained a Daspletosaurus in early stages of decomposition, where the bones were still articulated and loosely held together, though some were washed further on. Unfortunately, we think that's where the right leg ended up. We were 75 million years too late.
Original and printed bones, various colors of PLA
OK, so I had to sculpt one bone by hand


So what can we do? A one legged Daspletosaurus mount looks stupid. In the old days we would sit down with some material, a ruler and our eyeballs and sculpt the mirror image by hand. Luckily we don't live in the stone age anymore and instead we have computers and lasers and hot plastic.

Project layout. Pete's skull will be about 1.8x the size of the cast on the table.
We were missing one phalanx completely, so we laser scanned one from our Albertosaurus cast, blew it up to size, and then printed it. The entire right foot was scanned from the left, mirror imaged in the computer and then printed in full scale. We're still in the process of scanning the femur, tibia and fibula, but instead of printing them (which would take a lot of time) we are sending the files to someone with a 5 axis CNC router to carve them for us. Work smarter, not harder!