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.

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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.

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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.

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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.

Dimetrodon sighting

In search of it’s next meal, a very rare young Dimetrodon stumbles upon a group of working paleontologists…surprised, its fin stands straight up in a threat display, and it’s front two killing fangs are poised for action…

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Juuuuuust kidding.
They’re really much bigger than that.

Luckily for our paleontologists, I’m just kidding – this is not a creature you would ever want to run into alive. They were the top predator of their time, about the size of a Bengal tiger when they were full-grown – and just as mean. On the other hand, they lived about 290 million years ago, and show evidence of being early ancestors of mammals – like you and me. So it might have been pretty cool to see one alive – at least for the few seconds you had left.

Led by Dr. Bakker, the paleontology team has been searching for Dimetrodon in North Texas for over two years now – and they’ve made some fascinating finds. For the last week, they’ve been running their annual Paleontology Field School for educators. During this program, science teachers learn to dig for fossils, and then take what they’ve learned about geology, paleontology, biology, anatomy and more back to their students.

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A tiny Dimetrodon vertebrae found at the site the team
is working on in the background.

More than just digging up bones, the team is working to unravel the entire ecosystem of the Permian period, as expressed in the Red Beds of North Texas – the best beds for fossils of this era, in the world. It’s extremely slow work – once a fossil has been found, no matter how tiny (and some are almost ridiculously miniscule), it must be logged, mapped into place (this information is used for futher study, back in the lab), and then removed for preservation.

Significant, larger finds are jacketed first, with plaster, to be excavated further back the museum in Houston or in the Paleo Prep Lab at The Woodlands Xploration Station.

mapping

Carol, a teacher from the Houston area, assists in
mapping a site, using a Sharpie to trace their shape
on a thin sheet of plastic. Later, the maps will be
scanned into the computer for analysis.

Once they are digitized, the maps will help reconstruct the death events that took place – was this fossil a part of one individual – or another entirely? Was this Dimetrodon tooth shed in the act of eating a Xenacanth shark? – which will contribute to a better understanding of how these animals related to one another.

Dimetrodon fang

This is a great find – a huge Dimetrodon fang, one of the largest Dr. Bakker has ever seen. This photo shows what a fossil from this area looks like when you uncover it; now, it must be mapped in place before being removed from the site and packaged up and stabilized for the trip back to Houston.

Excavated

Once it has been excavated, you can see the same fossil fang a bit more clearly. If you look closely, you can see that the serrated edge of the tooth is preserved and still visible – almost 300 million years after this Dimetrodon died.

collared lizard

The wildlife around Seymour is surprising – jackrabbits,
roadrunners (meep, meep!) and much more. This
collared lizard energed from its burrow under a rock to
circle the site, vigorously bobbing it’s head at us (which
is how it says “Back off! This is my turf.”) – which seems
comical until you realize how hard they bite.

They’re still working out at the site; over the weekend, they discovered a new Dimetrodon skull, a fully articulated Diadectes hand (which is rare, because hands and feet are normally the first part of the body to be eaten or wash away) and a Dimetrodon scapula and humerus in perfect condition, and still attached. We hope to have photos for you soon. In the meantime, a new group of teachers joins the team today – who knows what is yet to be discovered?

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The thrill of discovery
comes with a price.