The secrets of earth’s ancient history buried at the end of the world

By Felipe Trueba

Cerro Guido, Chile, Apr 1 (efe-epa).- A valley at the southern tip of Chile, dubbed the “Rosetta Stone” of paleontology in the Southern Hemisphere, is providing an international team of researchers with new findings of well-preserved fossils of vertebrates, invertebrates and plants from the Cretaceous Period that could be the key to unlocking the secrets of life and the planet at the end of the dinosaur era.

The research by a group of geologists, paleobotanists and biologists in Las Chinas valley, located on a sprawling estate normally used for cattle farming that houses a treasure trove of fossils at the end of the continent, is also shedding light on the common past shared by South America and Antarctica, as the director of the Chilean Antarctic Institute (INACH) and director of this long-term paleontological expedition, Marcelo Leppe, tells epa-efe.

“It’s an iconic place with a lot of animal and plant species and microfossils that are helping us elucidate an unknown area of natural history,” Leppe adds.

The most southern outcropping of dinosaurs in South America, and in the world (with the exception of Antarctica), the abundance of fossils are explaining areas of natural history that have stumped researchers for years.

Sixty-six million years ago, an asteroid hit the Yucatan Peninsula in Mexico with catastrophic consequences on Earth: a worldwide climate disruption that triggered a mass extinction in which three quarters of plant and animal species died out at the end of the Cretaceous Period.

The Cretaceous-Paleogene boundary (known as K-Pg) marks the end of that era and the beginning of the next, the Paleogene Period.

The K-Pg is, in fact, a geological feature, often a thin band of rock that allows paleontologists to locate the exact timing of the dinosaur extinction, and which has outcrops in Patagonia.

This layer, and previous ones denoting the Mesozoic Era, are the point of study of another lot of experts – paleobotanists.

This team is continually finding fossilized leaf imprints, ferns and even seeds dating back 70 million years that reveal the former subtropical region with lush vegetation and higher sea levels.

“In this valley, we have found such a complex flora, with which we can use different methods that allow us to estimate the average temperature at the end of the dinosaur era,” says Leppe.

“We found that indeed there were large fluctuations in temperature, much of them drops, which are marked by sudden falls in sea levels. And that’s the moment that we find large quantities of dinosaurs and plants in this valley.”

Leppe, who has led a joint expedition deep into the heart of Chilean Patagonia every year for the past 10, says the findings lend more weight to a global trend of scientists beginning to understand that the dinosaurs might well have died off due to systemic climate change, rather than a sudden, external force like the asteroid that struck what is now Mexico.

“(The research) is linked to our growing understanding that prior to the extinction of the dinosaurs and prior to the Chicxulub impactor in Yucatan, the world was already convulsed by these climate shifts, and the evidence is here, in this valley,” the expedition director says.

One of the teams on the journey has discovered a range of species, such as Hadrosauridae (Duck-billed dinosaurs), Ankylosauria (armored dinosaurs) and even parts of large predators that complement earlier findings and provide the team with the missing knowledge they need to build a fuller picture of the earth’s ancient history in that pivotal age.

“We have some of America’s oldest mammals in this valley,” says Leppe.

“But its value is not only due to its age, it’s that these are pieces that were missing which have revolutionized our thinking, and allowed us to rattle the cage of our understanding of the evolution of mammals in the cretaceous period.” EFE-EPA

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