Abandoned quarry the site of world’s oldest known forest

Cairo now has the distinction of being the site of the oldest known forest in the world.

A study published this month by Current Biology described fossilized tree roots found in an abandoned quarry near Cairo.

Researchers determined that the ancient forest at this site lived some 385 million years ago. It is about two to three million years older than the previously designated oldest-known forest site, located in nearby Gilboa, N.Y.

The Cairo quarry is not only the oldest forest site — researchers discovered extraordinary fossils there, evidence that modern trees began to

develop much earlier than previously thought.

Researchers found surprisingly modern, complex root systems from the ancient tree forebearer, Archaeopteris. The root systems ran as wide as 11 meters across and went deep into the ancient soil (called paleosol), with branching rootlets.

Unlike more fern-like tree-forebears, Archaeopteris had woody trunks and flat, webbed green leaves.

“Evidence at Cairo suggests that the root system of Archaeopteris probably functioned in much the same way [as modern trees],” write the authors of the Current Biology article.

It was previously believed that this more contemporary type of ancient tree evolved in the late Devonian period (roughly 419 to 358 million years ago). This evidence at Cairo shows that it developed much earlier.

Trees and the spread of forests over the earth changed the earth drastically by absorbing massive quantities of carbon dioxide, creating a more oxygen-rich, cooler atmosphere, more conducive to the evolution of mammals. But much about the evolution of trees is still not understood.

The findings published this month represent a big step forward in our understanding of the evolution of forests, and indicates new directions for research.