Researchers have identified the world’s oldest known forest in the eastern Catskills.

The site, located outside Cairo in Greene County, is about 2 million years older than the title’s previous holder, located just miles away in Gilboa.

Fossilized remains of three different species move back the date when the ancestors of modern trees developed and give clues as to how their carbon dioxide intake may have affected the development of the atmosphere as we know it.

Researchers led by scientists from SUNY Binghamton and Cardiff University in England started examining the Cairo site in 2009 and published their findings in December’s Current Biology.

The Catskills looked drastically different during the life of the Cairo forest, explained William Stein, professor emeritus of biology at SUNY Binghamton and one of the site’s main researchers.

It was 385 million years ago, the mid-Devonian period. The climate was sub-tropical to temperate and the area consisted of wetlands, according to the Current Biology article.

The Catskills were not a group of smooth mounts as they are today, but instead a large plateau. To the east rose a massive sierra, the Acadian Mountains, as tall as today’s Himalayas, which formed when the North American Tectonic Plate collided with smaller plates from the east. To the west was a giant inland sea, the Appalachian Basin.

Rainwater flowed down the Acadians and over the plateau on its way to the inland sea, eroding the plateau’s weaker areas until all that remained were the Catskill Mountains we know today.

But 385 million years ago, the Cairo site was on the shore of the Appalachian Basin, Stein said, susceptible to floods from the sea. During this time, a flood washed over the Cairo site – Stein said it was unknown if was brine from the sea or fresh water from a storm – pushing sediment over the area.

“We’re talking a couple inches of a finer grade material, but it may have been enough to kill many of the trees and preserve the roots for us,” Stein said.

The researchers have identified fossils of three distinct plant species at the site.

The first, Eospermatopteris, appears about a dozen times at the site. The palm tree-like plant was first identified at the Gilboa site and features a rudimentary roots system.

The second, Archaeopteris, was the “major takeaway” from the site, Stein said.

“It’s really interesting to us because it’s so modern in many respects, and the rooting system is remarkably modern from the site,” he said.

Though Archaeopteris, which was not found at the Gilboa site, did not have seeds, instead reproducing through spores like fungi, it was the first known plant to have leaves and a root system that continuously expanded, suggesting a tree with a long life.

The Archaeopteris root systems found at the Cairo site were more than 30 feet in diameter and consisted of as many as 10-15 primary roots branching from what were probably central trunks, according to the Current Biology article.

The researchers also found a third, “enigmatic” root system at the Cairo site, according to the article. The tree matched most closely with lycopsids, a group of plants thought not to exist until almost 30 million years after the Cairo site was preserved.

However, Stein urges caution with the discovery. Lycopsids were thought to have arisen in Carboniferous coal swamps and the evidence collected at the Cairo site does not prove the tree existed in the mid-Devonian.

“But if it’s true…these plants that are so characteristic of the Carboniferous coal swamps environment are present much earlier in time, but not in a coal swamp, which may suggest they actually evolved somewhere else and moved into those swamps later in time,” Stein said.

Even if this is not the case, the Archaeopteris specimens found at the Cairo site are now the oldest discovered tree.

Archaeopteris was closely related to modern seed plants, with its root systems, leaves, and what was essentially modern wood, Stein said, and were a “quantum leap” from earlier plants.

The earlier emergence of the Archaeopteris might affect how the development of the earth’s climate occurred, since trees suck carbon dioxide out of the atmosphere and replace it with oxygen.

“We know that in the Devonian, CO2 levels in the atmosphere drop about this time and result in reduced temperature levels on the earth and a glaciation at the end of the Devonian,” Stein said. “So, you have evidence of glaciers as a major change in climate, perhaps related to the beginning of forests on the land surface.”

Stein calls this a “huge theory,” both in the sense of it being significant, and it still being a hypothesis in need of further examination. However, what might have happened 385 million years ago could have huge implications today.

“We’re in the opposite situation – we’re losing forests and of course burning a lot of the material that was in forests…and we’re increasing CO2 levels, and we’re worried about temperature rise, so we’re studying the problem in the reverse,” he said.

Studying the drop in carbon dioxide levels and how it affected the climate might give insight into how today’s climate will be affected by carbon dioxide rise, Stein said.

Stein and the other researchers are done with the site for the moment, which is municipally owned. He hopes Cairo preserves the site from collectors, suggesting it would be a great spot for field trips from schools or science camps.