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!

Thursday, March 6, 2014

Megalocoelacanthus revisited: New skull restoration

I know we've been over giant coelacanths from Kansas before on this blog, but they're so strange and rare that we can't get enough of them. Combine that with the fact that besides Hugo Dutel et al's paper on this specimen and this blog page, there is a dearth of information out there on the web about this critter. Consider it public education.

Megalocoelacanthus in all its glory
Megalocoelacanthus is known from just 2 specimens in Kansas: the holotype specimen that we prepared at the RMDRC that now resides at the American Museum of Natural History, and a second far less complete specimen that I discovered back in 2007, which Mike Everhart are hopefully publishing on in the near future (no pressure, Mike). The holotype was molded and cast several years ago, and we also molded the principal coronoid off of the second one to fill in a missing part for a more complete skull. Our first attempt was done without taking out any of the flattening distortion that is common in the Niobrara Chalk, and the results can be seen here. Over the past several weeks, Bryan Smalls has been attempting a second restoration attempt with guidance, assistance and not-always-helpful commentary from yours truly. The results were much improved.
total skull length is approximately 65 cm

Huge gular plates 
One thing we learned in this project was that people really need to illustrate certain parts of coelacanth anatomy better. Specifically the inside of the mouth and how the cliethra attach/fit. Also how catazygals go along the notochord. Get on it, smart people!

Almost dorsal view showing neurocranium ornamentation

Thursday, February 20, 2014

And now for something slightly different

You all deserve a brief respite from the dead fish and Avaceratops update barrage. What better excuse to talk about our big Daspletosaurus Pete III then? It's about the only dinosaur we have that people tend to ask about anyway. We've had an opportunity to catch up on a few projects lately and are able to spend some time in preparing the final few bones from their field jackets, while also restoring the skull bones to get them ready for 3d laser scanning and printing.

Bryan finishing the neural arch of caudal 2
I'm sure you have heard about the special challenges that preparing Pete III poses. I even did a paper on it, which is posted on my academia.edu page. When done, the bone itself is pretty stable, but it just looks somewhat ugly since it's made up of thousands of small fragments. We've adopted a technique using tinted hydrocal to fill in these small surface gaps to help give the bones a little more strength as well as make them look less pixellated (to borrow a term from a friend).
Left jugal after initial prep
Left jugal beginning restoration
Left jugal after finishing
Pixellated right quadratojugal

Much better with plaster
And in further comparison to the size of Pete III vs. Tyrannosaurus rex, here's a teaser comparing the left ectopterygoids of our Daspletosaurus vs a mounted copy of a rex. Not a whole lot of difference there overall.
Can't wait to get finished with this head...

Tuesday, January 28, 2014

Avaceratops skull finished - Tucson out the door

So, we here in the lab have survived yet another pre-Tucson Gem and Mineral Show crunch. Barely. This year we are exhibiting our casts at the 22nd Street Show. Come by and see our new stuff, like the Megalonyx, Enchodus, Stangerochampsa and our new Avaceratops.

Pinchy!
Never thought that pile of bones would turn out like this
Speaking of that, the prototype is finished! We molded the masters and then cast them using a rotational casting machine. Very lightweight! The finished skull is 1.05m (3'5") long from rostrum to end of parietal.

First run of the 3d model made from photographs
Very cute, and since the brow horns are pretty darn near symmetrical, their tweezer-like form is probably real. Very different than Nasutoceratops or even the MOR specimen of Avaceratops that Penkalski and Dodson described. What that means precisely is something for the experts to work out.

Human for sacle
The Enchodus is also pretty darn cool looking. Coming in at just 5 feet long (1.7m), it's one of the scariest looking little fish I've ever dug up.


Enchodus prototype

Stop by the booth and check out the specimens. And if you would like a copy of the Avaceratops, tell Mike I sent you. He;ll give you a good deal.


Monday, January 6, 2014

Avaceratops Skull Resto



Cast mount of the holotype Avaceratops in Philadelphia
So after a year and a half of digging and preparation, what do you do with a big pile of bones? Put them together! At long last, our Avaceratops project is moving forward and is surprisingly starting to look like something. Avaceratops is a fairly poorly known animal, with only 2 partial and fragmentary skulls discovered before this one. Ours is filling in lots of gaps since 1: we have more bones than were known before and 2: the bones that we have are more or less complete, not busted up. This adds a degree of difficulty to the project since all the restorations done before made a few educated assumptions about their missing bits, and not all of those were accurate.
An older bone map of the skull bones we thought we recovered, based on an image by Scott Hartmann
Jaw bones both real and 3d printed
Where to start though? In treating this like a giant model kit, we first decided to make all the parts we needed. There will be 60 individual bones to deal with. While we have the lions share of those, we do not have them all. The first step is to mold all the original elements and cast them in plastic. This enables us to mount them and take distortion out without destroying any of the real fossil. Second we identified all the elements that we had one side of and needed the other. Those elements were laser scanned, mirror imaged in software, then printed out in plastic on one of our 3d printers. Lastly, some elements were flat out missing. Those were fortunately few, but they ended up getting sculpted.
So, let's begin with some parts. Boot for scale
Once the parts were poured, we cut apart a few casts where the bones were glommed together and it was too dangerous to try to pry the fossils apart. After fitting a few parts, some needed to get cut or bent to fit how they were supposed to, taking millions of years of crushing and distortion out. This is much trickier than it sounds. Our frontals were squished just enough in the ground that when the brow horns were attached to the mount, the tips crossed each other. That's probably not how they went in life. The casts were then adhered together into subassemblies ready for molding.

Where we are today.
Work is still ongoing but we hope to be done in the next week or so with the heavy work. Once the molding is done, the final product will be just 5 parts. Much easier to put together than 60.


Tuesday, December 17, 2013

Giant Oviraptor Tracks from the Hell Creek

It's been known for years that there are oviraptor-like dinosaurs found in the Hell Creek Formation. We find isolated elements mostly. A pubis here, a claw there. Small snapshots into their world, but they don't answer deeper questions like how big they got, how they moved, where they lived (instead of just where their remains ended up).
Skeleton of the new Hell Creek Ovi

In 1997 Mike Triebold was scouting on private land in Harding County, SD for dinosaurs. He came across a strange looking concretion. It looked a bit like a footprint, but as we know, concretions can take on all kinds of shapes. Looking closer, there was another concretion, in the same shape nearby. Then another and another, all in a line. A small excavation was started into the nearby outcrop, and the line of concretions continued. Though the overburden was getting too deep to chase them futher, it is likely there are even more still at the site. Mike recovered the specimens and made them available for research, which will be published on shortly.

Tracks in situ. The largest are nearly 60cm (2ft) across
Excavation of tracks
The concretions have now been identified as a preserved as the trackway of a giant North American oviraptorid, much larger than the specimens that we have skeletal remains for. The trackway shows how fast the animal was moving and even what kind of muck it was trudging through. We made molds and casts of the best ones, I'm thinking it may be a great addition to our ovi display in the exhibit hall.

Thursday, November 14, 2013

3d scanner and printer up and running

After several years of fighting with technology, our 3d laser scanning program is up and running here at the RMDRC. We're currently scanning original specimens that are in the restoration queue in order to generate mirror image parts for missing bones. We started with simple parts on the Avaceratops including cranial and limb material, and progressed to more complicated things like the dentary and maxilla. Not satisfied with the amount of punishment we dished out on ourselves, we then tried Enchodus bits like the super thin premaxilla and operculum. They all turned out extremely well.

One of our new printers which works surprisingly well
Now that we have more complete sets of replicas to work with, our restoration of these specimens will be not only much more accurate but also faster.

Avaceratops lower jaw, with white 3d prints of actual material

Avaceratops tibia, split in a computer so it could fit in the printer
Next on the docket is some of the cranial material of our Daspletosaurus specimens. Donor parts from other animals will be brought in and scaled to size. Surprisingly easy to do with the software and operators we now have here. If you are out there and need some items scanned, give us a call!