Thursday, February 23, 2012

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

Tuesday, February 7, 2012

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.