12: Crossing the Finish Line with a Surprise

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Transantarctic Mountains
© N.D. Smith
Ornithischian Quarry

In the last dispatch, I covered the completion of the Cryolophosaurus quarry excavation, but there's one more video rounding out that subject. Check out "Excavating Cryolophosaurus Bones: Part 3,” which captures Bill Hammer’s reflections on bringing this 20-year endeavor to a close, and the process of crating and airlifting our 5,000 pounds of fossil-bearing rock from CTAM back to McMurdo.

With the Cryolophosaurus quarry completed—and only a few days left to our dig season—Nate, Eva, Phil, and Peter were joined by Adam and Roger on Mt. Kirkpatrick. This was Adam and Roger’s first and only chance to visit the dinosaur locality, and we were anxious to have Roger apply his stratigraphic expertise. Our goal was to have him log a detailed vertical section through the rock layers bracketing our quarry to provide us with a better context for placing it within the section for the whole Hanson Formation.

While most of the team set about sawing out the isolated bones discovered on the previous day, including the thrice-discovered ischium, Roger worked his way up the layers of sediment, walking not only uphill, but ranging widely to the left and right to interpret the depositional history of the rocks. In Roger’s own words, the section was rather “boring,” with little in the way of neat sedimentary structures or associated trace fossils or plants—with one important exception.

As he was logging under a sandstone overhang, Roger came across several small bones about 30 meters south of the main quarry and a few meters higher in the rock section. It turns out that the bones Roger found were all in a line in the rock and included sections of vertebrae, as well toe bones and what looked like a hipbone (see Photo #1 below.) These bones clearly belonged to a single animal and appeared to be mostly articulated, with the joints between bones still in place. (To see Roger’s finds, and to get a look at the ischium that Eva found, take a look at the Video Report, “Surprising Discoveries!”)

Even more exciting was the fact that these bones came from a bipedal herbivorous dinosaur far smaller than either Cryolophosaurus or Glacialisaurus. Unlike Cryolophosaurus or Glacialisaurus, which are both saurischian, or lizard-hipped dinosaurs, our new find was the skeleton of a primitive ornithischian (bird-hipped dinosaur), and therefore a member of the lineage that later gave rise to such famous dinosaurs as Triceratops and Stegosaurus.

Ornithischians are very rare in the Early Jurassic period, and currently the best skeletal remains of the most primitive members of the ornithischian lineage come from South Africa and Lesotho, so this find promises to be significant in several ways. But, with only one day’s worth of helicopter time left in the bank, we were under the gun to excavate Roger’s find quickly.

Nate, Phil, and I boarded the helicopter and shuttled off into a bright blue sky for one last day on Mt. Kirkpatrick. The small ornithischian skeleton was exposed in a near vertical rock face under a deep overhang. The three of us had to crouch down and work in a confined space using an electric jackhammer as well as conventional hammers and chisels. All of us knocked our heads on the overhanging sandstone ledge more than once (see Photo #2 below.)

We started working towards the front of the specimen, taking out a large block that contained vertebrae, and with any luck, skull parts. The next steps in the excavation process were tougher. The exposed bones represented the animal’s back, with the limb and girdle bones projecting into the rock.

Given the cramped confines of the quarry and the time crunch we were under, we tried to carve out a series of blocks containing bones by chipping away the rock above the bones and then chiseling the blocks free from below. But by mid-afternoon, we got worried when our generator started coughing and struggling. It was leaking oil badly, and we called in one last favor and had another generator brought in by helicopter to ensure that we could complete the job.

The second block we worked on contained a section of two limb bones in articulation, which we first interpreted as the knee, largely based on the bones’ sizes. Primitive Early Jurassic ornithischians from southern Africa, such as Lesothosaurus, Stormbergia, and Heterodontosaurus, are small animals, no more than a meter and a half in length and less than two feet tall, and the size of the exposed bones seemed to fit with what we knew of the hind limbs of the African species.

But, as we worked backward towards the hips and tail, we realized that our knee was actually an elbow. Since these animals have much shorter forelimbs than hindlimbs, this could only mean that we were dealing with a somewhat larger species new to science. This observation fits nicely with the trend we see in the other fossils from Mt. Kirkpatrick.

The dinosaurs we find on Mt. Kirkpatrick are, thus far, unique to Antarctica, and also are as large or larger than their contemporaneous relatives known from other continents. We shouldn’t get ahead of ourselves before the material is back in the U.S. and prepared, but it’s certainly an intriguing pattern, with a possible biological explanation known as Bergman’s Rule.

Bergman’s Rule states that for closely related species with a wide geographic distribution, species from polar regions tend to be larger than their relatives from lower latitudes. Perhaps we have evidence that this applied to fossil faunas as well as modern ones—it will be a question we pursue as we prepare and study our new discovery.

By late afternoon, we’d gotten much of the vertebral column, the forelimbs, parts of the hips, and hind limbs. Some of the smaller bones of the tail and the pelvic bones were exposed in cross section on the wall of the quarry, but were impossible to excavate in the time left to us and with the increasingly deep overhang we were working beneath.

In fact, we even made the decision to leave our packs and gear on the mountain in order to take all the fossil material with us on our return helicopter flight, not being certain that the weather would hold for one last trip to recover our equipment. Although it was a bit disappointing to have to leave some fossils behind, we were pleased that we’d managed to collect the majority of the specimen in such a short time.

After dragging the block of bone and the remaining excavation equipment down to our cliff-edge helicopter landing zone, we had a little time to sit and relax and take in the incredible view from Mt. Kirkpatrick one last time (see Photo #3 below.) Feeling content with what we had achieved under some of the most difficult conditions I've ever worked under in the field, it was a bittersweet moment.

We'd achieved, and in some ways, surpassed our goals, and I was getting anxious to get home to my family after a long absence. But the thought that this would be the last time in years, perhaps forever, that I would look out over this incredible landscape of ice and rock above the Walcott Névé, at the far end of the earth, left me with a note of sadness and a deep appreciation for the unique opportunity I'd experienced.

The rising thunder of approaching rotor blades ended my moment of quiet reflection. Soon we were on our way back to camp to celebrate with the rest of our team in our communal yellow tent.

Farewell for now,
Pete

© N.D. Smith
Ornithiscian Bones
© P. Currie
Excavating the Ornithiscian
© P. Makovicky
View from Kirpatrick