Reconstructing Chelosphargis: What to do with a pile of bones

We spend a lot of time in Kansas hunting for specimens in the Niobrara chalk. A whole lot of time. Luckily the soft chalk erodes pretty quickly so we also find a whole lot of stuff. Occasionally though, other people also get lucky and we'll happily take the specimen off their hands. In early 2015 this exact scenario played out. You may have seen the result at our display booth at SVP this year in Salt Lake City, overshadowed by our exciting mount of our Daspletosaurus "Pete III"

Curator shadow selfie while digging in Kansas recently

A poorly collected turtle specimen from the chalk was being shown around looking for a buyer, While the collection techniques caused some damage to the fossil, it was plain to see a fairly complete tiny Protostegid was encased in the slabs of yellow rock.

So, this is how we got it. Clearly not how we would collect a specimen.

Most importantly, almost all of the skull was there, which is really nice. We immediately acquired the specimen and prepared the parts. Quickly it became evident we had a older subadult specimen of the relatively rare taxon Chelosphargis advena, an 84 million year old relative of the much larger Protostega and Archelon.

The parts after prep

Skull partway through prep

As you can see, most of the animal was there, in fact it's one of the most complete Chelosphargis specimens ever discovered. But what do you do with a pile of bones once they're all prepared? We're one of the few places with the knowledge, experience and capability to do a complete cast restoration without damaging the original bones. The first step was to mold everything as-is, so we can have parts (sometimes even multiples) to work with.

Cast skull copies getting cut and shaped to take out distortion

Distortion is taken out of the plastic and missing parts are either fabricated from similar ones from this animal, scanned in and resized from other specimens, or in rare cases done the old way with sculpting from reference material.

Carapace getting parts added and completed

The restored parts are then molded again in units so that we can make our final copy and offer it to museums and the general public as a highly detailed cast skeletal mount, perfect for display anywhere. The entire project only takes a few weeks, but the result is pretty phenomenal!

Final product!

Our newest little turtle: Jubal

Apparently TPI is the new home for the small turtles of the Niobrara chalk. We've already prepared, molded and cast our tiny Chelosphargis advena, Prepared a new Prionochelys matutina, and show prepped a nice Toxochelys latiremis that we discovered this past spring, all with nice skulls.

Our Prionochelys matutina specimen from MU5 (Coniacian)

You'd think that we would be content with our fossil turtle stash, but no. You can never have enough of these little guys. This week we prepared from start to finish another new specimen of a tiny protostegid from Kansas.

Box o rocks and bones

Preservation of the bones was beautiful, in nice hard yellow chalk so prep was an absolute joy. We didn't collect this specimen ourselves, which might explain the slightly unorthodox packing method employed in shipping the bones.

Plastron during preparation

While prepping the slabs we discovered many bones that were not apparent when work started. many of these surprise elements were adhered to adjacent bones by a thin layer of the oyster Pseudoperna congesta, making separation much more difficult.

Detail showing much of the pelvis in place

Amazingly, we are 4 for 4 this year for beautiful turtle heads. The skull block on this specimen contained not only all the major head bones, but also most of the hyoid apparatus. A very rare find in animals this small in the chalk.

Skull block before prep

Partly in thanks for helping us determine the identity of this turtle (the uber rare Chelosphargis advena), and partly just because we like him so dang much, we nicknamed RMDRC 15-001 "Jubal" in honor of Dr. Kraig Derstler of the University of New Orleans. For the back story, well you're just going to have to ask him about it.

Profile view of skull after prep

When finished with the prep, we did a layout and were shocked how complete this specimen really is. Next up is restoration, molding and casting so copies can be exhibited in museums and homes worldwide. The specimen is currently displayed in our lab viewing area, so come by soon and check it out before we put it all back together.

This is what a turtle looks like if you crack it open and pull everything out

It's Tucson Time Again

Sorry for the lack of updates. We're working on a ton of new projects this winter for an awesome Tucson gem and Mineral show. A few teaser pics, more and better ones as we get closer to shipping the show. Now back to the salt mines.

Enchodus vs. Hamburger-sized turtle

Newest fish

Headbutting Sandy

Cap'n Chuck's back end