HIPS HIPS HURRAY! [Dimetrodon Fossil Update]

Your HMNS field crew and lab staff score the missing pelvis!

Willie the Dimetrodon continues to command the attention of your Paleo Dept. personnel. In May through June, David Temple led an intrepid crew who gently lifted the plaster jacket containing Willie’s torso, shoulder and rump. Local ranchers Donny Gale and Gary Max Coltharp once again generously donated their time and machinery – especially useful was the Coltharp front-loader named “Lola.”

But still – though Willie is among the very finest D’dons anywhere, he had a pelvic deficit. Check out this hip diagram.

CB-WilliHipsEdge

Willie’s sacral ribs are there, the parts of the vertebral column that hold the hips. However, the hip bones themselves are still missing. Probably some hungry scavenger came by and bit these meaty bits off (one rib was twisted out of place too  and the lower left shoulder had some bite marks).

“Locality Edge” comes to the rescue. Discovered by a local science teacher four years ago, Locality Edge is an awesome outcrop of badlands, full of tortuous arroyos, box canyons and spires of red rock. The strata here are just a bit later than our Craddock Bone Bed and about a mile away. We removed a pelvis and set it in a drawer.

c-Willi-Edge-Pelvissmall

We did note that this set of pelvic bones was unusual – the shape was not distorted by the tons of rock that had buried it. Most of the time the burial layers flatten out natural curves of the upper bone, the ilium, and the wide lower bones, pubis & ischium. The Edge pelvis miraculously survived 285 million years under the rock layers. The lower bones kept the strong inward curve that the living animal had.

c-williedgevaronicasmll

The thought erupted in our minds: Could the Edge pelvis fit our Willie? Was it big enough??

Was it the correct species? We took the pelvis out of its museum tray and I brought it to the small but excellent prep lab at the Morrison Museum in Colorado (located a short drive from the famous Coors Brewery). The Morrison Museum generously opens its facilities for special Houston projects. Thirty hours of work later, with the assistance of three delicate pneumatic chisels, the outer form was cleaned of the rock (note the specimen in the skilled hands of a Morrison volunteer at right).

Superb!  And  when the inner surface of the ilium was placed next to Willie’s sacral rib, they clicked together precisely.  The size was perfect. So was the shape – the Edge specimen clearly came from the same species and the same body size.

Now, the pelvis is getting its final beauty-treatment at the skilled hands of volunteers at the Houston Museum prep lab.

Thus the contributions of a dozen volunteers and staff, plus two labs, has taken us one step further in getting Willie up on his feet, to delight and instruct  HMNS visitors.