Xiphactinus project update

Yep, it's still ongoing.

We have assembled the skull, vertebrae and caudal fin into the mount, and stuck on the first layer of our fake matrix. We remove all matrix from the specimen and make our own for one very good reason: natural chalk is very soft, and is prone to breaking and cracking. It usually offers no meaningful support for the specimen, so it is better for us and the fossil to remove it completely and install our own.

Jacob hard at work filling gaps between vertebrae with epoxy putty

Next up on the docket is to lay out the sets of ribs and pectoral fins, and fasten them to the mount. That process should take about a week, so check back on the next update for progress!

Xiphactinus mounting: The beginning

One of the "nearest forest fires" in the lab lately is getting the world's largest Xiphactinus audax skeleton, RMDRC 08-004 "Mildred" prepared and mounted. These fish are traditionally done as a panel mount, since usually they are a bit flattened, especially with articulated skull material. Single-pieces are preferred since mating up seams on a big flat panel is just kinda ugly. Unfortunately, when dealing with a mount of the biggest of anything, that usually means a BIG mount.

The underside of the skull. We put a support material on this side to stabilize the bones

In this case, the panel is sized to 7 feet tall and 21 feet long, the appropriate size for an 18 1/2 foot long fish. It's going to be heavy no matter what we do, but our goal is to end up with a contraption weighing in at about half a ton or so when we're finished. One can dream.

Just a small fabrication project

We've already finished preparation of Mildred's bones, as well as the needed parts of the "donor" parts fish that would be used to fill in pieces lost to erosion or scavenging sharks. On the 3 fish, we've recovered well over a dozen shed Squalicorax falcatus teeth that were lost when the carcasses were getting scavenged.

Jacob and Lisa bolting the plywood to the frame

The next step is to position the bones on the panel and affix them to the background material. We use some cast parts, as well as the complete skull, vertebral column and tail to get an idea of the size, pose, and margins of the fish. It's always good to figure this out before we start attaching stuff with adhesive. On the downside, it doesn't look very pretty yet, but it gives us a glimpse of how the final product will look.

As of this morning, with the body outline sketched on

 There's still a lot of work to do, but we're confident we can make the deadline now.

Soft tissue preservation in a Platecarpus

This past week we were able to do a bit more work on a specimen that we collected last spring with a student group from the University of Tennessee-Martin. This small mosasaur, a Platecarpus planifrons RMDRC 11-001,  was just about the only recoverable mosasaur material seen on that trip. This specimen was discovered by a UT-Martin student, and the discovery, excavation and recovery process was recorded by a UT-Martin journalism student group.

How many people can you fit on one digsite?

The specimen was brought to the lab and awaited the UT-Martin student group to come to Colorado to prepare it. That chance came this week. The skull was weathering out first, and the roots of nearby plants had started growing around the bone making preparation a bit tricky. The students and film crew covered the preparation of the torso and neck, which was in much better condition. I was left to work out the skull.

Partially prepared torso, neck and head

We were paying special attention for anything that would tell a story about the animal. First we discovered gouges from shark bites on the lower jaw, then a shed sharks tooth at the left articular. While slowly preparing around the quadrate, we located the extracollumnellar cartilage, a semi rigid plate that often gets mistaken for a calcified tympanum. I waas shocked that this was still present with so much root infiltration. later while preparing between the pterygoids, small remnants of the tracheal rings were also discovered. I expected them there if present since they tend to get blown forward through the mouth after death, looking like a linguine dinner after a hard night of drinking. Unfortunately, no skin was present on this specimen, but as always, we'll be keeping an eye out

Can you spot the tracheal rings?

Tracheal rings in another specimen, this time a Clidastes

The things you find when you work on stuff

Mildred's skull, with blue tape to mark parts that need to be removed

We've almost entirely finished the preparation of RMDRC 11-021 "Lois", the last parts donor fish for our reconstruction of RMDRC 08-004 "Mildred". We've been going through some of the pieces of chalk that fell out of the huge main jacket when it partially collapsed when we flipped it for removal from the digsite. Sometimes these things happen, especially when the chalk is weathered and fractured.

Feathery and fine gill structures articulated with the arches

Surprisingly one of the chalk pieces produced something very rare: the actual preserved gill structure of this Xiphactinus. Usually with most Xiphactinus specimens, the disarticulation of the skull by scavengers results in these delicate structures being lost. On articulated skulls, they are likely present however no one ever starts removing bones to investigate if they are indeed there. For now they remain pretty rare things. We won't be using these in our restoration, hopefully we can find a good home to donate them to.

Jacob and Lisa fastening plywood to the steel tube frame

In other news on the reconstruction front, we've finished building the frame for Mildred. 21 feet long, 7 feet tall, it's going to be 150 square feet of big bad X-fish. Nearly time to put it on a rolling stand so we don't have to lift it ever again!

Lois gets prepped! Mostly!

It is unusual for us to move so quickly from collection to preparation and mounting, but sometimes the stars align. We're currently working on mounting the largest skeleton of Xiphactinus audax ever found, RMDRC 08-004 "Mildred". Unfortunately, the sharks got ahold of the carcass before it sank to the seafloor. They eviscerated it, and it is now missing most of its secondary fins, as well as chunks of ribs and spines. For a display specimen, this isn't really ideal, so we're using a few donor fish (ones that are way too incomplete for display on their own) for parts. These will be incorporated to complete the skeleton of the mounted fish, and their parts will be documented so not to make anyone think the composite skeleton is just a single animal.

Initial site view at TPI takeover

Jackhammers are a backsaver

Lois (RMDRC 11-021) was discovered early in 2011 by another fossil hunter that had mistakenly been scouting on property that was under contract with TPI. No big deal though, our crews came out to the site shortly afterwards and recovered the specimen.

Later in the day, big big hole

It was largely disarticulated and found with its caudal fin rays all around the skull region: the proverbial "head up it's butt" position that we frequently find fossil animals. The low rise over the fish was removed with a Bobcat and we set about finding the perimeter, or extent of the specimen.

Mike with chainsaw, Jacob for scale (2 meters)

Unfortunately the jackstrawed nature of the bones meant we'd have to remove the main part in a substantial field jacket. I don't like doing that, big jackets are heavy.

Cleaning the undercut for jacketing

Lois has somewhat flakier bone than usual for a fish, mainly because much of it was near the erosional edge, making preparation a bit slow and less than easy. The smaller jacket is nearly finished, as well as the individual parts we were able to remove on site. The large jacket may take a few more days to show prep, due to the bone condition. It will however be very useful in completing the original bone mount of Mildred, which will be started in the next week.

Just a photo of learning marker units in the field

Bad day for a bad fish

Comfortable working conditions as usual!

As far as bony fish go, Xiphactinus audax was the king of its ocean. They reached insane lengths, up to 18 feet in articulated skeletons, like our "Mildred" specimen recovered in 2008. In 2010 we recovered a second 18 footer that was discovered by a Boji stone hunter on a private ranch which we collect on. This specimen was coming out head-first (or more precisely, the entire site was pretty much the erosional edge due to very low overburden).

The site, extending from the orange paint to near the blue tarp in the background

Detail of some of the "wonderful" bone quality on the edge

The fish was pretty stirred up and not as complete as we'd like for a stand-alone specimen. The entire caudal fin had exploded into individual 3 foot long bony rays, the skull was pretty much gone, all the ribs were jackstrawed into a massive tangle. There it earned the nickname "Goober", as the specimen appeared pretty goobered up. Luckily, the fish could still be useful to us as a parts donor for the Mildred specimen, which will be panel mounted this coming spring. We worked hard for several days removing the animal in 3 large jackets, as well as multiple smaller ones. The chalk was a bit fractured but still pretty dang hard. Air hammers turned out to be a lifesaver when undercutting the slabs of bone.

Can you see the tooth? Internal surface of the sclerotic

As with any paleo lab, we have a big backlog of specimens that need preparation. This specimen wass tored in our lab till yesterday, when we began preparation. More on that in future updates. Working on the specimen revealed several interesting things though, stomach contents consisting of a 4-5 foot long ichthyodectid fish, as well as teeth left by the scavenging shark Squalicorax falcatus. This morning revealed the tooth of one of these sharks lodged inside the sclerotic ring of Goober. I've had bad days before, but I've luckily never had sharks-biting-you-in-the-eye bad days. Ouch.

Baryonyx in Colordo: 100th post

It's been 1oo posts since I started this blog. Some people would have something special planned out for an occasion like this. Plan? Why start now?

Amazingly, the post I did about a year ago on our asembly of a cast Baryonyx skeleton is still the main traffic driver on this blog, after the updates of course. In order to celebrate, I'm putting up a few more pics of the cast for future google image surfers.

With a copy of the Maidstone slab in the background

Nice paws

This specimen is on display for a few more weeks in the RMDRC, before getting shipped off to its new home overseas. 

34 feet (11m) long is big for almost any theropod