Satellite data can reveal large individual fossils from the air, allowing field researchers to embark on more targeted searches on the ground, research finds.
“Organizing field work is very expensive, and there are lots of safety and security risks,” says Elena Ghezzo, who led the work as a postdoctoral researcher in the lab of University of Oregon paleontologist Edward Davis. “So any additional information you can have from the field before you go is useful. My method seems be really good at ruling out regions that don’t have fossils.”
The team analyzed multispectrum satellite imagery, which includes not just visible light, but also other wavelengths like ultraviolet and infrared. By looking at how the landscape absorbs or reflects all these different types of light, researchers can pick out specific features, like fossils, from the background.
This kind of satellite data is often used to do aerial surveys of cities and track patterns of land use. But it hasn’t been used before to search for single fossils, Ghezzo says.
The researchers tested their idea with data from Petrified Forest National Park in Arizona. More than 200 million years ago, this landscape was a lush coniferous forest. Today, it’s a colorful desert, dotted with fossilized logs. Based on a reference map they created by hand, the researchers could identify the signatures in the satellite data that distinguished a fossil from the background or from other landscape features.
To be picked out via satellite, a fossil must be bigger than a single pixel in the image. And its mineral composition must respond differently to light than the surrounding material. It’s easier when the landscape is flat and open, with relatively few obstructions, as the Petrified Forest is. But other data about the geology and topography of the region can also be factored in, to help researchers distinguish a fossil from, say, a tree or a big rock.
Ghezzo is now testing the technique on a variety of fossil sites around the world, from Peru to Egypt to Mongolia. And closer to home, Davis is particularly interested in applying the approach to some of his team’s field sites in Eastern Oregon.
“There’s a lot of places in the interior of Oregon that are very difficult to access even today,” Davis says. “Having the ability to use aerial photography to find fossils could help us allocate our resources.”
More broadly, a technique of this kind could be part of a shift within the field of paleontology. The practices of the past, which included blowing up hillsides with dynamite, have, in some cases, irreparably damaged the landscape. A new generation of paleontologists is working to make the field more sustainable and preserve the context in which fossils are found.
“We don’t do a lot of digging anymore,” Davis says. Instead, researchers often wait for fossils to be exposed by erosion, and then excavate in a more targeted manner. And satellite data can help them out.
Their findings appear in the journal Geological Magazine. Ghezzo had a Marie Skłodowska-Curie global fellowship to pursue the project.
Source: Laurel Hamers for University of Oregon