Page 2/2 - Posted April 15, 2011
Fossil hunters take big haul despite tough conditions
As Smith tells the story, the team was excavating a Lystrosaurus, one of the common therapsid herbivores, when they found the remains of a Prolacerta-like animal resting underneath. It’s the most complete and best preserved skeleton of this type of animal in the region, he said.
“This thing is beautiful,” Huttenlocker said.
Another intriguing find came from Graphite Peak, but in the geological formation directly beneath the Lystrosaurus-bearing rocks. A handful of bones here and from Coalsack Bluff, not yet identified, are about as close as scientists have come to finding actual bones from before the P-T boundary in Antarctica. Plants flourished during the Permian — and numerous fossils have been collected over the years — but never anything from a vertebrate.
“Of course, years of collecting [in Antarctica] means a few months,” noted Smith, referring to the short field seasons available to researchers in such remote polar locations.
The handful of earliest Triassic bones includes a clavicle that appears to belong to an amphibian and a partial skeleton of a small reptile.
“We’ll be able to fill in the story better of how vertebrates came down here and when precisely they came down here,” Huttenlocker said of the finds. “It’s filling in a little bit more of that story of what’s going on earlier on. We still don’t have a good Permian record yet, but we’re working our way down.”
A PhD student with Sidor, Huttenlocker’s research involves the growth strategies used by vertebrates as they passed across the extinction boundary. Did they grow smaller (a pattern observed following other extinction events)? Did they shorten the time it took to grow to adulthood? To answer such questions, he looks at the microstructure of the bones.
“I take priceless fossils, relics from antiquity, and cut them up, to look inside their bones so as to look at the growth rings that they record,” he explained.
Huttenlocker can compare growth rings between animals in Antarctica and the Karoo Basin, for example, to see if they grow differently in different environments.
The comparison is particularly apt because scientists like Smith believe the two ecosystems, joined together in Pangaea (and still later as the southern supercontinent Gondwana) were remarkably similar. Even down to the fauna.
“It’s been quite a revelation to find not just the same animals, but the same down to species level, to prove there was genetic flow between South Africa and here,” he said.
One difference between the two places is the ease in which the fossils can be extracted.
Antarctica is not just a tough place to visit. The rocks undergo little weathering, so those that are exposed are in the sort of condition one might expect to find several meters below the surface.
For extraction, jackhammers give way to gas-powered, diamond-bladded rock saws. “Saw down, chisel out, saw down, chisel out,” said Smith, almost like repeating a mantra.
Added Huttenlocker: “It’s no trivial task. This is the hardest rock a paleontologist will ever work on.”
Of course, even to get to the point of sawing into the rock, one must first find the fossils. A trained geologist, Smith seems to possess a particularly keen eye for spotting irregularities in the rock that might indicate a fossil is lurking nearby. It’s also a matter of confidence, he said.
“It’s not a matter of if you are going to find it, but when,” Smith said. “We have definitely done what we came out to do. We came out to find fossils in these places, and we have done it.”
In fact, the team collected about 40 specimens, which should arrive at UW in Seattle this month, according to Sidor.
One specimen that didn’t make it back was an exposed fossil — a rib cage or backbone — that Sidor found buried under about a meter of rock in 2003 but didn’t have the time or tools to retrieve.
“I wasn’t able to relocate the specimen at Fremouw Peak,” Sidor said later via email. “However, that didn’t matter, because we found so much more that it was probably our most productive locality.”
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