Friday, December 21, 2012

Restoring a Protostega

Back in October of 2011, the lovable TPI field crew was brought out to a ranch in western Kansas (very near the site of Sternberg's famous "fish within a fish" specimen) to help with the recovery of giant sea turtle. This turtle skeleton will be reposited in the Sternberg Museum of Natural History at Fort Hays State University. The term giant is used loosely here, since the actual turtle was only about a meter in shell length, nowhere near the car-sized members of its genus that would later cruise the oceans. Field photos shamelessly borrowed from Mike Everhart's wonderful Oceans of Kansas website.

Making the hole bigger with power tools. Also shovels.
The turtle site was located fairly low stratigraphically, and was entombed in a fairly hard grey chalk. Our first order of business was to identify the bone layer and then break out the power tools to remove the overburden from a wide area. I'll say it again, that cute little green jackhammer is a backsaver!

Mike Everhart and I jacketing the slab, with the finger hair saving nitrile gloves
Once down to the bone level we perimitered the specimen, cut around with the chainsaw, and jacketed the whole slab.

Perimitering in the quarry
Exposing more of the bones
That was the easy part! Back in the lab we began by using air abrasion and pneumatic scribes to remove the matrix from the fossil, first the individual bones that were collected before TPI arrived.

Individual bone before prep in the lab...
...and after air abrasion, scribe and glue work
A few interesting surprises popped up once I started removing the chalk. Abrasions on the ventral side of the plastron seem to indicate this turtle pulled itself up some distant beach, possibly suggesting it was a female getting to dry land to lay its eggs, though some modern male sea turtles also come out of the water occasionally. The carapace and especially plastron were covered by what look a heck of a lot like puncture wounds, all unhealed. The front flippers were totally lacking any parts below the elbow, in fact one humerus was bitten completely in half. It sure looks like the turtle was a partial meal for a mosasaur like Tylosaurus before it finally sank to the sea bottom.

Abrasion and puncture marks on the plastron
Once the bones were prepared they were all molded individually (when possible). The casts were then manipulated into larger assemblies, where we filled in missing parts and took out some crushing distortion. These assemblies are then used to make production molds for cast copies.

Carapace subassembly in a thixotropic mold
Original bone pile being molded for parts. 
We should have the project done in the next few weeks, just in time to display at the Tucson Gem and Mineral Show this January. Stop on by to check it out!

Wednesday, October 31, 2012

Still prepping the Avaceratops

Though I had a good time attending the SVP meeting in Raleigh, NC this month, it put me a little behinf on prep work. Jacob was able to join the preparation frenzy and between the two of us we've gotten a lot done.

Nasals, showing strange asymmetrical suture
Getting the individual bones prepped out of their jackets is giving us some valuable insights. Though the bones are well preserved, each one is getting its own custom made Hydrocal support cradle to keep them from getting damaged during storage.

The deep and short left dentary, with all teeth
We've uncovered the brow horns now, prepped out the left lower jaw, and finished the nasals. If you're in town you should consider stopping by to get an up-close look at the material. It's some strange stuff!

Strange centrosaurine brow horn, resting in its cradle

Thursday, October 4, 2012

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 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

Wednesday, September 26, 2012

More with Avaceratops

We just got back from the final dig of the 2012 season in the Avaceratops quarry. The weather was outstanding with sun, highs in the 80s and lows near 40. Getting a little chilly in my tent, but nothing uncomfortable.

A few of the epoccipitals. Not very big or pointy.
When we decided to take a jackhammer to the overburden we had only recovered some postcranial elements and one part of the frill, the right squamosal. Many hours later we had blasted out several tons of rock from above our bone layer, and were able to get digging.

The smallest group jacket, with at least 4 bones
To our surprise, nearly all of the bones found in this expansion of the quarry were disarticulated parts of the skull, including some parts that had never been seen before in this genus. We recovered (so far) 8 epoccipitals, the predentary, and a complete jugal (all new), plus both postorbital horns, a left dentary, nasals, maxillae, the other squamosal, and both splenials. There are even more bones in the blocks that we couldn't get a good look at yet, so completeness should further increase.

left Nasal, very well preserved

inside of right maxilla, with a few teeth still in place
I am interpreting the site as a logjam along the southern edge of the quarry, made of (now) carbonized conifer trunks and surprisingly the limb of a very large hadrosaur, the femur measuring a whopping 1.25m long. Check back for more photos as prep continues, and stop by the lab for a look if you are in Woodland Park!

Thursday, September 6, 2012

Digging Avaceratops

It seems just a week ago I was in the badlands of central Montana picking at bones in concrete-hard sandstones of the Judith River Formation. The locality we worked at the end of our trip is known for a nice productive channel lag deposit that gives up claws, teeth, and moderately sized dinosaur bones. Occasionally there are more than a few bones in one spot. We happened upon one of these spots in the lag and discovered a partial skeleton eroding out of the bottom of the exposure. Already a good find in the difficult to scout JRF.

The author, picking away at hard rock

The beginning of opening the quarry

The bones turned out to be from a single Avaceratops, one of the rarest horned dinosaurs in the Judith River Formation. We recovered what bones we could from the hard rock using hand tools, and plan on returning to the site at the end of the month with heavier equipment to get down to the bone layer. So far we've recovered parts of the skull and skeleton yet surprisingly no vertebrae. Hopefully much more of this animal is locked safely in deeper rock.
The right squamosal
The same bone, showing the 3 characteristic bumps
This is a fairly small juvenile specimen, probably only 12 feet (4m) or so in total length. Two of the elements that we recovered tell us this dinosaur is Avaceratops: The squamosal (part of the bony frill) has a series of distinctive bumps on its lateral surface that only happens in Avaceratops. The second bit is a tiny ungual (hoof) of the 4th finger, which is lacking on all other North American ceratopsians.

Scapula and coracoid in preparation

Check back with us and see how the excavation goes. We will be bringing in our trusty electric jackhammer and air tools to open up the quarry. We should know more about what is present beginning in October.

Friday, August 31, 2012

When will the heat end?

Over 110 degrees on the outcrop. Ouch.
We are back, finishing our Hell Creek Formation field season and starting our Judith River Formation work in South Dakota and Montana. The fires are pretty bad out there due tot he drought, and silly high temperatures are the norm for now.
Not quite a dinosaur

We located a few specimens including a juvenile ceratopsian in a pretty tough sandstone, and we will be returning in a few weeks to collect the rest. Enjoy the photos!

Oh look! A Pachycephalosaurus!

Heat makes Jacob feel kinda stabby

Just south of the Canadian border

I will replace my Estwing with a jackhammer next trip

Ceratopsian squamosal

Rib, ungual, and scapula/coracoid of the ceratopsian

Friday, August 3, 2012

Sometimes you get the Trike, sometimes it gets you

Jacob and I are back from a second trip to the Hell Creek, working on some sites we discovered on the first trip. We spent the majority of our efforts on the site that produced the left brow horn form the first trip.

Beginning of the dig. Chunky bone fragments circled in orange paint.
We expanded the excavation to the north by about 8 feet, tracing a few bone fragments. The overburden was low, and digging relatively easy, but the bone exposed were rounded isolated small chunks. Not especially promising.

Braincase with distinctive ball of the occipital condyle
As we worked back closer to where the brow horn was found, we started encountering more recognizable bones. Unfortunately, the skull was all that was present, and even then it was partial. In the end we recovered a squamosal, predentary, braincase and maxilla, along with some fragile fragments that will be worked on in the lab.

First batch of bones jacketed, waiting for plaster to cure

End of the dig. The generator and electric jackhammer was a real back-saver!
Headed back out in a few weeks, hopefully more luck then!

Friday, July 20, 2012

Back to the Hell Creek

We're headed back out to excavate a few of the Triceratops sites that we discovered during our last expedition. We didn't waste any time in the lab though, and did a little bit of work on some of the specimens we brought back from or first trip.

Jacob's femur dig site
Jacob discovered a Triceratops femur in a channel lag deposit, directly downwind of a recently deceased cow carcass. It's now being fully prepared (and as it turns out, is only a partial specimen) as a touch bone for a museum opening soon.

Lots of bone chunks on either end, but the main portion is nice

The turtle that I found the first day of the trip has now been identified as Stygiochelys estesi, with a distinctive scallop on the rear end of the carapace.
That's a nice turtle

On the last day of the last trip I discovered the left brow horn and a few other bones of a large Triceratops prorsus.Preliminary preparation of the horn revealed two large and mostly parallel gouges near the distal end. These grooves have bone surface on the bottom and could be interpreted as healed bite marks from an attacking Tyrannosaurus rex. They definitely are not due to crushing or postmortem damage. Exciting stuff!

Triceratops horn site
The show-prepped horn

Grooves outlined for clarity, they do not photograph well

I will update our progress again when we get back from our next trip. Hopefully we will be low on plaster and packed to the gills with fossils!

Thursday, July 5, 2012

Post wildfire fieldwork update

First the good news: Ute pass is now open and so is the museum. Please stop by and visit!

The bad news: The fire was pretty bad. 18,000 acres burned and 350 homes lost, along with 2 deaths. The fire impacted me personally by coming down the mountain and burning within just a few blocks of my home. I was certain for a while that the house was lost but the firefighters saved it in the end. I'm just back from a week evacuated out of the state.

I'll need some help identifying this turtle once it is prepared

Previous to that, however, Jacob and I (and for a little while Mike too) were in South Dakota scouting for new dinosaur skeletons on a 2-week trip. We left most of the material in the ground for now, however we will probably recover many of the 7 dinosaurs that we located at a later date. A smattering of photos below for your enjoyment!
Big old pile of Triceratops bones

Jacob working on a Triceratops on top of a butte

Articulated scales on a mostly articulated gar

Triceratops site discovered on our last day. Jacket is one brow horn.

Friday, June 1, 2012

Helping with museum renovations

I'm a little late to the party, but I wanted to share this link:

A few years back, a crew from TPI took down the Apatosaurus skeleton from the University of Wyoming Geological Museum, reprepared and stabilized the bones, then remounted the skeleton in a more modern (non tail-dragging) pose. Recently the museum has been slated for renovations/asbestos abatement so I was sent up to help Dr. Kelli Trujillo and Bill Turner remove the tail (and a Pteranodon cast, and also an Allosaurus, at least in part) from display so work on the museum could commence.

The tail will be back on display later this year, just in case anyone is concerned. It should be viewed as a minor miracle that I actually made it that far up on a scissor lift. I don't do heights well. You can see a complete cast of this Apatosaurus on display at the RMDRC.