A day in the life of a Daspletosaurus bone

Some people asked me not too long ago about what we do in order to get some of these bones ready for molding. In the case of Pete III, our Daspletosaurus from Montana, the condition of the bone gave us some additional problems. All specimens of course get excavated and painstakingly prepared by our expert staff, but in Pete III's case, even the prep necessitated the invention of new techniques which I published on a few years back. The entire specimen was pixelated, with some bones made up of hundreds of thousands of fragments. Lots of glue was needed to even expose the bone, which is huge, literally Tyrannosaurus rex sized. Once done the left ilium looked kind of like this:

Next up is reconstruction of any major missing bits and holes with epoxy putty like Aves Apoxie Sculpt. That's the grey stuff.

We then apply a barrier layer of B-72 to hold everything together for the next steps. Shiny!

Then we take our gorgeous bone and smear the whole thing with tinted Hydrocal.

 Yuck. OK now it doesn't even look like a fossil. Never fear, most of it will be gone soon. The main aim is to work the Hydrocal into all the seriously tiny cracks in the surface to better hold the bone together. This also reduces the amount of the relief in the specimen so molding goes much faster. The excess on the surface is removed with air abrasion.

Doesn't look so shiny anymore, but we can fix that with a wee bit more of very thin B-72.

And there you have it, one half of a bone restored in a few days time. Now we just make a support jacket so the entire thing can be flipped over and the process repeated.

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

Atractosteus from the Hell Creek

I feel a bit guilty. I found a gar specimen last year, in a soft sand, and I was afraid to prepare it. I had nightmares of thousands of bony scales floating loose in space. Well this week I finally took the plunge and started work. I've even been able to identify it to genus (I think). Let's start at the beginning.

June, 2012:

Hey look, a fossil! Toes for scale.

While prospecting in far western Harding County, SD for typical latest Cretaceous dinosaur fauna, Jacob and I climb a really high butte to GPS a Triceratops and see if it's on our landowner's property. No luck, it's a few dozen yards too far south. From up high we see a few very small low outcrops on our landowner's side of the fence that probably should be checked out. Jacob heads towards the pond, I trudge up to a sand blowout about 5 feet high at the most.

Scales in the field

The gar was just laying there in the flats. The scales caught my eye first, then I noticed the vertebrae, and the faint outline of a skull just barely coming to the surface.

Finishing the perimeter and consolidating

We treated the specimen like ones we dig up in Kansas: no need to expose any more, just find the perimeter. If you hit bone (or scales) just move on in a wider circle. The sand was so soft that we did all the work with mason's trowels. In about an hour or so, the site was perimetered.

Jacket's done!

I was fearful that no matter how good of a jacket we made, the thing in the loose sand would collapse out of it as we flipped the jacket, so I made the call to saturate the topside of the block with B-72 to harden it at least a bit. The hydrocal jacket was then applied directly to the rock, no separator being used. By lunchtime we had the jacket under control. Back in the lab, it sat under a workbench for over a year.

October 2013:
The specimen, now known as RMDRC 12-008, alternatively "ValDaGar" after my wife (plus it's really fun to shout), is brought out of storage. I figure it would be good to at least get the skull exposed, if it's there, before SVP. It'd suck to show up a second year in a row and tell researchers "no, we still haven't worked on it yet". After removing a few inches of sand (we dug deep JUST IN CASE) I finally hit something hard. Luckily it was bone, not the other side of the plaster jacket.

Here's where to start

Ok, I admit, it doesn't look pretty

Exposing the skull took surprisingly little time. I moved a bit further back to see if there was indeed articulated body. There was indeed. Every one of the hundreds of scales is getting prepared individually. I'll let the photos speak for themselves

Much better

The body slowly gets exposed

Side of face floated off a bit

Prepping the Avaceratops

It's long overdue for an update, and since the weather in Montana isn't cooperating with our plans to head up there today and finish our season in the Judith River, it's as good a time as any to show what we've gotten done in the lab.

Newer modification to Scott Hartman's illustration: now with no nose horn

Work is slow due to the fact that the bone of this juvenile animal is fairly soft and crumbly when not consolidated, and that many bones are jackstrawed together in larger blocks. Each bone is individually removed from its jacket and checked against the field inventory. When it's a new bone, not exposed in the field excavation, we give it a separate accession number to keep track of it in the lab.

Jacket disassembly with documentation

Typical multi bone jacket before removal

We're primarily using air scribes on the "firm" sanstone matrix, with air abrasion for the detailed work. In some cases, such as the extensive skin impressions over the left hip and rib area, we skip the abrasion in order to preserve the skin as best we can.

Skin texture preserved on the right ilium

Once out of the rock, we restore the cracks and missing bits with epoxy putty in order to get the bones ready for molding. Our current plan, due to the completeness of the skull and skeleton, is to mold everything and do a full skeletal restoration. The animal looks like it will be less than 1.5m tall at the hips - very manageable for a ceratopsian.

Molding jaw parts prior to laser scanning

Enchodus rears it's head!

Over the past few weeks, Jacob and I were out doing some scouting and excavation in the lower Niobrara chalk in western Kansas. With the recent drought in the area, not much erosion has happened and so specimens were a bit tough to come by. Though we were blessed with instructions to just record fish localities, secure them, and move on, sometimes the fish are just too good to pass up.

Enchodus palatine fang eroding out

One of our long term goals is to expand our 3 dimensional fish reproductions from Kansas. We've completed 4 so far (Xiphactinus, Ichthyodectes, Saurodon, Pachyrhizodus) and we're working on Megalocoelacanthus as our 5th. Enchodus has always been on our wish list (one of the most common fish in the WIS, and those fangs... people love pointy parts), however the large specimens of Enchodus petrosus are very rare, especially anything resembling a complete skeleton and not just isolated palatine bones with fangs.

RMDRC 13-001 fanf after prep

Jacob struck first with a very large Enchodus fang protruding from the grey chalk between MU 7 and 8 He took down the overburden and exposed a sizable disarticulated skull with pectoral fins and vertebrae. We prepared a good portion of it in the lab and have decided that this specimen is where we will mold the majority of the individual elements from.

RMDRC 13-001 digsite

A few days later I was working an outcrop slightly lower (just above MU 6) and was shocked to find an articulated skull weathering out of some seriously soft chalk. I hoped it was attached to the rest of an Enchodus.

RMDRC 13-005 as found

Originally we were going to "Sternberg" the specimen (pouring plaster directly over the exposed bones to stabilize everything in the jacket) assuming that there was more resent at the site. Unfortunately, sometimes all you get is a head. In this case a giant one (lower jaw 25cm long) indicating an overall length of about 1.25m. This will be the basis for our overall reconstruction.

RMDRC 13-005, bottom side prepared

We're hoping for the prototype to be completed and ready for SVP at the end of October. Fingers crossed.

More Mosasaur Fun, Complete With Spectators

Just finished a sort of long-term new project for us. Occasionally we get requests from museums and universities to come out in the field with us and collect specimens. Even more occasionally, we oblige. In 2011 a class from the University of Tennessee - Martin (actually 2 classes, one in geology, one in journalism) came out to our digsites in western Kansas to find and document fossils for a new museum project. TPI fieldcrews supervised and instructed, however we let the students do the finding. They came up with several neat little fossils (several Spinaptychus, a Chelosphargus partial skull, Martinichthys skulls) and lots of partial fish. On the second day, one student hit the jackpot: the tip of the lower jaw of a mosasaur poking out from just under the alluvium. 

Ever feel like you're being watched?

Here, Aaron (the discoverer) works to remove overburden from the specimen. TPI does the same thing, though usually with fewer spectators. He decided to name the mosasaur "Kimberly". I've named specimens worse things I suppose.

Digsite viewed from across the gully, right near MU 5

 The specimen was tentatively identified int he field as Platecarpus planifrons. Though reasonably well articulated, it was missing the front limbs and everything back behind the mid dorsal vertebrae. UTM students preimetered, stabilized and jacketed the specimen. Most importantly they also carried the slab across the badlands to the nearest truck, which was great for me!

Standard TPI field photo pose, before jacketing

Back in the lab, preperation was begun by UTM students under TPI guidance. Mosasaurs are usually pretty straightforward to work with, however this one presented a few challenges. The proximity to the alluvium meant that this specimen encountered some weathering back during the last ice age, and roots made matters worse. The prognosis was grim initially, as the bone and teeth looked to be in pretty rough shape. But careful consolidation and prep resulted in not only stable bone, but the discovery of the preserved remnants of tracheal rings, as well as extracollumnellar (ear) cartilage. At the rear of the left lower jaw, one of the scavenging sharks, Squalicorax falcatus, left its calling card.

Kimberly's skull

Next up the specimen will be delivered to the new museum in Tennessee, where it will go on display later this year. Luckily the whole process was documented by the journalism students, almost from the instant of discovery. If I see the video, I'll post a copy on the blog in the future.

Not a bad little mosasaur.

Avaceratops Prep Update

We're on to the big jacket!

Current map of confirmed bones. Base image courtesy Scott Hartmann

Thanks to Scott Hartmann and Skeletaldrawing.com for permission to use his image of Avaceratops' skull.

The big jacket, still in preparation

I haven't had an opportunity to expose everything in here yet (there are both postorbital horns hiding deep in this jacket) and I have removed 4 epoccipitals and an epijugal from the mass already, but here it is! Shown in all of its partially prepared glory you see both premaxillae, as well as one each squamosal, jugal, and quadrate. I also have 3 mystery bones comprising a possible parietal or exoccipital (wingy-thing part of the braincase), a possible palatine and another super thin feathery plate.

The next step is to repair my air abrasion unit, cut down the jacket a little bit, and then look for those horns. I'm avoiding removing anything else since everything is so jackstrawed. Combine that with some surprisingly thin and fragile bones, and we could end up with a real mess on our hands.

Bones piled on other bones

Fragile and strangely shaped bones, these take a long time to prepare, only 25-30% done

Show Thescelosaurus some love

When is a dinosaur not a dinosaur? When it's fairly dull I guess. Just look at Thescelosaurus. Not brainy, not much in the way of fangs, claws, armor, clubs, or anything else sexy. It's also a fairly rare dinosaur, with just a handful of reasonably complete specimens. We at the RMDRC have been lucky, preparing the only complete skull so far (on "Bert"), as well as now preparing a pretty dang complete skeleton, "Jonathan".

Right leg from the former display

Jonathan was discovered in 2006 in the Hell Creek Formation of Montana. It was nearly complete, minus the tip of the tail and the head/neck where it had eroded out into the gully. Lying belly-up, once show prepped, it nearly looked like it died just yesterday.

Main jacket

Look at that cute little first chevron

We have now started to prepare all of the bones free of the matrix. We will restore them, mold them, reconstruct the missing bits, and offer a cast of this big Thescelosaurus (13-14 feet or 4m long) for sale to institutions. The original will be mounted in 3d on a steel armature. That last bit is a LOT of work, but it's also pretty satisfying and a bit of fun too, especially if you enjoy doing metal work!

Daspletosaurus prep update

Jacob and I have been hammering away at the remaining small jackets of Pete III. By small I mean things less than the 4 ton main jacket monstrosity that we'll eventually have to confront. This week we've finished the left femur and ilium, along with a slew of gastral elements, vertebrae, and other bits and pieces.

Anterior dorsal of Pete III compared to Stan

The ilium has a strange mass of punky bone on the medial face of the pubic peduncle. We've seen a few instances of old age related pathology on this specimen, it wouldn't surprise me to find more.

Medial surface of left ilium, 42 inches long

Before long, we'll be started on the pathological tail section. Can't wait!

Caudal view of left femur.

Daspletosaurus prep restarts: this time with skull bones

While I was away soaking up pathogens at SVP in Las Vegas last week, paleotech Jacob Jett has been busy preparing some of the jackets from the weathered edge of Pete III's excavation. The bone was in difficult shape to begin with (earning the nickname "The pixelated Tyrannosaur" at SVP) before seeing several hundred Montana freeze-thaw cycles, making this prep work one of our greatest challenges to date. However, results are here! Skull bones so far include both quadrates, a jugal, both quadratojugals, a spenial, pterygoid and possible surangular, with more to come. No toothy bits yet though.

The left quadrate. Actually recognizable!

Dorsal vertebra #1, giving you an idea of the sheer size of Pete III. Transverse process span is 15 inches (38cm)

Surprise! Manual phalanx!

We still have many jackets (including the majority of the big 4-ton monstrosity) to prepare, however we're confident that the majority of the skeleton and perhaps 20-30% of the skull is here. Check back for more updates!