Welcome to project "Yogi-Fido" - the preparation of an extinct 30 million year old "Bear Dog" from South Dakota.
So let's start with a few facts about this specimen:
Species: Daphoenus superbus (suspected anyway)
Family: Amphicyonidae - Bear Dogs
Period: Oligocene - Whitneyan - Poleslide Member - Brule Formation
Age: 30.58 million years ago
Location: White River Group Badlands, Custer County, South Dakota
"Bear-dogs" were an extinct group of large carnivorous mammal that survived from 45 - 2 million years ago. There were many species within this family but there are no living members of this group remaining. Although they have morphological features similar to those in both bears and true dogs (canids), they are not a member of either of these groups. They're a group of completely unique predators! To read a more detailed overview, click: https://en.wikipedia.org/wiki/Bear_dog. The Bear-dogs had a range of different sizes, but Daphoenus superbus was a large species - about the size of a large wolf.
So what does this specimen look like?
Below is the original photo of the specimen still in it's make-shift field jacket when it was found during the 2015 season on a Private Ranch in South Dakota. This was found by a local expert in Oligocene Mammals who has quickly roughed-out the skull to help identify the creature but the rest is totally unprepped. At half a meter in length and weighing over 50lbs, this is a massive chuck of matrix which will take some time to fully expose the beast within!
Looking closer at the matrix once exposed, you can see bone fragments sticking out everywhere. Below is a video I took of opening the package when it arrived from South Dakota. The skull is clearly visible but so are scattered vertebrae and rib bones poking out.
The Skull
The skull is about 20cm in length and looks in decent condition but there is damage to the Zygomatic arch, back of the jaw and the two exposed canines are missing their tips. The bone also looks fairly flaky however I believe this is the part of the skull that was exposed to the elements so is probably weathered to a greater degree than the unexposed bone. It's a shame that the canines are both broken but fingers crossed that the other side of the skull has a least one canine in better condition so that you can get an idea of their predatory biting power.
The Skeleton
Based on the amount of random bone poking out, there is certainly some skeleton in the matrix. You can see on the surface a number of vertebrae, rib bones and possibly part of the sacrum. They do look very scattered however which suggests that this skeleton has been scavenged after death with bones more jumbled as a result. I can't see any limb bones, but they'd normally lie towards the bottom of the matrix. I'd estimated 15-25% of the skeleton is probably locked into this block of matrix.
The Preparation
This is a very rare species to find so I want to be very careful with this and take my time. I suspect this will take at least 20-30hrs to prep out fully and to make robust & displayable. The plan is to use a pneumatic air scribe (Paleotool ME-9100) to remove the bulk of the hard matrix. As the fossilized bone is exposed, I'll use a diluted 5% Paraloid B72 / Acetone mixture to consolidate the bone and to stop further fractures or breakage as the air scribe's vibrations can be damaging. This Paraloid formula (see previous blog for details) helps protect and strengthen the fossil bone - especially when it's brittle and flaky. Once most of the matrix is removed, I'll work on the finer detail with an air abrader which is a micro-sandblaster using a 50% mix of Dolomite powder and 50% Calcium Bicarbonate. This will help remove the last bits of matrix and make it more presentable. This is the plan anyway....
Wish me luck and keep a look out for update on this Yogi-Fido project.