Slideshow: Fossil Hunting in the Andes
Central Chile's rugged Andes mountains preserve some of South America's best mammal fossils. But finding them requires endurance, persistence--and a willingness to climb.
view the slideshow Credits: TRYSTAN HERRIOTT
Even on days our fossil hunting turns up nothing new, we revel in the splendor of landscape all around us--such as this striking view of Antuco volcano from one of our localities in the Lake Laja region...
Rocky outcrops above the El Pino River in the Lake Laja region also turned out to contain ancient mammal fossils.
This precipitous site in the Cachapoal River drainage is where we discovered a five-centimeter-long skull of New World monkey we named Chilecebus carrascoensis. Note the person (inside white ellipse) for scale.
ANDR? R. WYSS
More often than not, fossil sites are far from even the most primitive of roads. Here some of our team is backpacking into a site a site about 100 kilometers north of Tinguiririca , in the drainage basin of the Cachapoal River . This locality produced one of our best fossils--the most complete skull of an early New World monkey ever discovered. ANDR? R. WYSS Advertisement
LOST IN LAJA:
Here we are somewhere in Estero Trapa Trapa (nearly Lake Laja) trying to figure out where we are. I (Wyss) consult the GPS while John Flynn (middle) and Darin Croft study the maps.
WALKING TO THE OUTCROP:
Even for areas that we can approach by truck, such as this one near Lake Laja, it is usually a fair hike to the outcrop for a day’s fossil hunting.
EASIER WAY AROUND:
Sometimes we can actually get a pickup truck within a few kilometers of a fossil site. Here are some of our crew members below fossiliferous outcrop we call Cerro Los Pinos near Lake Laja, which is about 300 kilometers south of the Tinguiririca valley.
NO HORSING AROUND:
Riding cross-country on horseback is another way we get around central Chile’s rugged terrain. On the day this photograph was taken, we had spent most of a day trying to find a suitable camping spot for exploring a promising locality near the Teno River. The guy on horseback on the far right is me (Wyss). The other people in the picture are Chilean geologist Reynaldo Charrier (standing) and two Chilean cowboys. The photographer was geologist Philip Gans, one of my fellow faculty members from the University of California, Santa Barbara. He recalls this day as being “fairly odd from a culinary standpoint.” Gans writes, “Andy and I set off on foot to explore, and everyone else and all the horses (and unfortunately all of the food) went back down to the drainage to find a different way up to our target site, so we did not see them again for about 6 or 7 hours. All we had had to eat that day was a little coffee (with milk from one of the mares!) and a little piece of empanada, so by the time we finally hooked up [with the group] again, I think Andy and I were pretty hungry. Actually, I was a little better off, because in my pack I was carrying two dozen fresh eggs. Along about mid-afternoon, I suddenly remembered I had these, and in desperation I ate a couple warm, raw eggs to tide me over.”
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In the spring of 1994, reconstruction of the small road leading into the Tinguiririca valley was especially slow, but we did not learn of this impediment until arriving on the scene. Turning frustration into an opportunity, we began explorations outside the Tinguiririca valley. We soon found more fossiliferous localities, and most of them were quite remote and only accessible by long approaches by helicopter or other means.
Here is team member Franyo Zapatta, a Chilean geology student, having just reached the fossil-bearing outcrop we call Tapado. Some of our best fossils come from this perch—Andy’s Rule strikes again! Tapado lies just a few kilometers west of our first discovery site in the Tinguiririca valley, but the mammal remains we found there are several million years older. This view is looking east, up the valley toward the town of Termas del Flaco, which is visible in valley floor (
white oval). ANDR? R. WYSS
TRICKY RIVER CROSSING:
We had to ford the raging Tinguiririca River without a bridge to reach the second major cache of mammal fossils we found in the Tinguiririca Valley. This photograph yet again encapsulates “Andy’s Rule,” which says that the harder an outcrop is to reach, the likelier it is to contain fossils. (The yellow box indicates the location from which following photo was taken, and the yellow arrow shows the direction of that view.)
ANDR? R. WYSS
This view--due east, with the skyline marking the border with Argentina--leaves no doubt about the incline of the slopes flanking the Tinguriririca River. For a sense of scale, look closely for our team’s cluster of half a dozen camping tents (inside the white circle), near the edge of the purplish-brown, fossil-bearing rocks. During three full field seasons prospecting this locality, we turned up at least 25 species of 32-million-year-old mammals--most of which are new to science.
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FOSSIL DISCOVERY TREK
After several hours of trudging up the steep southern slopes of the Tinguiririca valley near Termas del Flaco (which is visible in the valley floor), the two of us reached the highest ridge in the late afternoon. A bit disappointed about not finding any fossils on the way up, we looked for a milder route down. Not long after, we crossed a patch of volcanic sediments that turned out to contain remains of an amazing variety of ancient mammals, including an early sloth and a chinchillalike rodent.
ANDR? R. WYSS
Our first fossil reconnaissance trip to central Chile culminated here at the summer resort village of Termas del Flaco. On the last day of that expedition, we split up to prospect the precipitous slopes flanking each side of the Tinguriririca River, which flows briskly along the southern edge of the town’s hot spring pools. That afternoon, another team member and I discovered the first cache of mammal fossils in a layer of purplish-brown volcanic sediments nearly 1,000 meters above the valley floor.
ANDR? R. WYSS
Rocks exposed above central Chile’s Lake Teno contain fossil mammals buried in mudflows from one of this volcano’s ancient predecessors.
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