I used to love scrutinizing the rocks as I hiked. I hoped to find something important.
I’d find pretty green and pink rocks, rocks with interesting shapes, rocks that might have been carving tools, once a petrified twig. I’ve mostly stopped doing that, because I really don’t know what I’m looking for, or at.
But some others do, and they have found it—in abundance.
Paleontologists “spend a lot of time walking around with their eyes glued to the ground, because that’s where the fossils are,” said Calvin So, a paleontology student at the University of Wisconsin. I heard him a few weeks ago at the Riverton Museum.
Two days earlier, the crew of the Nobby Knob Triassic Expedition had covered over their site southeast of Dubois to leave it behind for the winter. They have spent this past summer excavating a trove of remains from what So called “the dawn of the dinosaurs,” between 230 and 200 million years ago, during the Late Triassic.
Team leader Dr. Dave Lovelace gave a similar presentation at the Dubois Museum in July, when I was out of town. My husband went, and phoned me afterwards with astonishing news: Lovelace and the team have been tramping around the outskirts of town for the past four years, searching and digging for fossils.
They’ve been defying the experts, looking for remains in a geologic stratum in Wyoming that paleontologists have referred to as “the big red dead,” always thought to be a dry and barren period devoid of animal remains. The fact that the team has proved them wrong should not surprise us in Dubois, where we know that dry and apparently barren does not imply a lack of life.
“We have found an abundance of fossils,” So said, “contrary to what other people have been saying.” Almost everywhere they’ve looked in the Wind River Valley, Lovelace told me, they have found fragments of bone from this period.
After finding a tantalizing whole phytosaur skull near Lander, where a few Triassic finds were reported in the early 1900s, the team began to explore the red dirt on public land almost within view of structures in Dubois. In 2014, they found fossil fragments of extinct salamander-like creatures known as temnospondyls. The next year they determined where those fragments had been eroding from. This summer, the crew was digging at that spot for two months.
Who knew that these guys (and women) have been out there, as they put it, “digging up Dubois” for four years? (“Anyone who is interested can see us from the main drag in Dubois,” Lovelace said.) And who would have guessed what they’d uncover?
The red hill they named Nobby Knob (after a character in a fantasy book series) has yielded what Lovelace calls “amazing” remains of creatures with the wonderful name of Koskinonodon, a genus of extinct amphibian. Among them is a skull, probably a juvenile, that they affectionately named “Wally.”
When Wally died, sometime way back in a period when the continents were in entirely different shapes and orientations, this area was covered with a shallow lake. Think, So said, of a creature lurking partly submerged, waiting for something to ambush.
Extracting the fossils can be brutal work. To extract the fossils from the dirt, they cover them with plaster. One plaster “jacket” containing dozens of stone-covered fossils weighed 500 pounds, So said. It took about 400 hours of work to chip away painstakingly at the surrounding rock in order to expose the fossilized bones. Another weighed about 1000 pounds.
Once the specimens arrive in Wisconsin, the team exposes the bones. Then they run them through a CT scanner and analyze them using a custom imaging program that allows them to discern the individual bones inside a skull.
In 2016, the team began excavating another site nearby that is rich with remains. Lovelace calls the Serendipity Site a “mass death assemblage.” It’s a Late Triassic cemetery of sorts; a large collection of burrows containing the fossils of tiny early amphibians, probably distant ancestors of the salamanders. Many of their skeletons are preserved largely intact.
This could be echoes of a distant climate change. So said these may be the remains of creatures that went into estivation – a sort of hibernation intended to wait out a drought – and were doomed when the drought lasted too long.
This site adds to another prehistoric distinction for Dubois: A curator of the American Museum of Natural History in New York has called this region “the epicenter of Rocky Mountain archaeology,” because the prehistoric high-altitude villages found above Whiskey Basin a decade ago have changed our ideas about some of the earliest Native Americans.
Now this site is changing the way we think about some of the earliest vertebrates. There are enough late Triassic fossils just east of town to classify Dubois as a “world-class vertebrate paleontology locality,” Lovelace told me.
There are only 5 similar sites in the world, he says, and “this one is unique even among those rare localities.”
The other sites (in Poland, Portugal, Morocco, and New Mexico) are “multi-taxon sites” that include remains of several different types of animals. Most of them are random collections of bones and skulls, not large numbers of complete skeletons. The Dubois site is unique, according to Lovelace, because it preserves a single type of animal.
The remains at Nobby Knob are extraordinarily well preserved, in part due to the slow, shallow waters in which they were submerged, still showing remarkable features such as tiny teeth embedded in the palate at the roof of the mouth. Also, the vast majority of the skulls are small, and “small individuals are exceedingly rare.”
This leaves a number of unanswered questions: Were they small because they were all young? (It is not uncommon for adults to inhabit different areas than their young to avoid “their young becoming part of their diet,” he says.) Or are they a new and different species?
And another intriguing question remains: Why were more than half of the burrows at Serendipity not found empty, but still encasing the skeletons of tiny creatures doomed never again to walk that alien, ancient landscape? What was the fatal factor?
The crew will return next year to continue work at the site.
© Lois Wingerson, 2018. Thanks to Dr. Lovelace for reviewing the text for accuracy.
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