Remnants of the world’s oldest fossil forest have been discovered in a sandstone quarry, providing fresh insight into the ecology and habitats of early forests.
It is believed the extensive network of trees, uncovered in Cairo, north of New York, is around 386 million years old and would have stretched some 400km to Pennsylvania and beyond.
Due to the fossils being located lower down in the rock sequence, the Cairo forest is thought to be around two to three million years older than what was previously the world’s oldest known forest at Gilboa, also in New York State.
The new findings, which have been published in the journal Current Biology, have cast new light on the evolution of trees and the transformative role they played in shaping today’s world.
A team led by scientists at Binghamton University, New York State Museum and Cardiff University have mapped more than 3000m2 of the forest at the abandoned quarry in the foothills of the Catskill Mountains in the Hudson Valley.
Their investigations showed that the forest was home to at least two types of trees: cladoxylopsids, primitive tree-fern-like plants, which lacked flat green leaves, and grew in vast numbers at Gilboa; and archaeopteris, which had a conifer-like woody trunk and frond-like branches with green flattened leaves.
A single example of a third type of tree was also uncovered, which remained unidentified but may be a lycopod. All these trees reproduced using only spores rather than seeds.
The researchers also reported a “spectacular and extensive” network of roots which were more than 11 metres in length in some places and belonged to the archaeopteris trees.
According to the study, it is thought the forest was wiped out by a flood. This was evidenced by the presence of many fish fossils that were visible on the quarry surface.
“It is surprising to see plants which were previously thought to have had mutually exclusive habitat preferences growing together on the ancient Catskill delta,” co-author of the study Dr Chris Berry, from Cardiff University’s School of Earth and Ocean Sciences, said.
“In order to really understand how trees began to draw down carbon dioxide from the atmosphere, we need to understand the ecology and habitats of the very earliest forests, and their rooting systems.” Berry said.
“These remarkable findings have allowed us to move away from the generalities of the importance of large plants growing in forests, to the specifics of which plants, in which habitats, in which types of ecology were driving the processes of global change.
“We are really getting a handle on the transition of the Earth to a forested planet.”