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Archaeopteris - The First "True" Tree

A Tree that Fathered the Earth's First Forest

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Archaeopteris

Archaeopteris

UC Berkley - Museum of Paleontology

Our earth's first modern tree establishing itself in developing forests emerged around 370 million years ago. Ancient plants made it out of water 130 million years earlier but none were considered "true" trees.

True tree growth only came about when plants overcame biomechanical problems to support additional weight. The architecture of the modern tree is defined by "evolutionary features of strength that builds in rings to support greater and greater height and weight, of protective bark that shields the cells that conduct water and nutrients from the earth to the furthest leaves, of supportive collars of extra wood that surround the bases of each branch, and of internal layers of wood dovetail at branch junctions to prevent breakage." It took over a hundred million years for this to happen.

Archaeopteris, an extinct tree that made up most of the forests across the earth's surface in the late Devonian period, is considered by scientists to be the first modern tree. New collected pieces of fossils of the tree's wood from Morocco have filled in parts of the puzzle to shed new light.

Stephen Scheckler, a professor of biology and geological sciences at Virginia Polytechnic Institute, Brigitte Meyer-Berthaud, of the Institut de l'Evolution of Montpellier, France, and Jobst Wendt, of the Geological and Paleontological Institute in Germany, analyzed a trove of these African fossils. They now propose Archaeopteris to be the earliest known modern tree, with buds, reinforced branch joints, and branched trunks similar to today's modern tree.

"When it appeared, it very quickly became the dominant tree all over the Earth," says Scheckler. "On all of the land areas that were habitable, they had this tree." Scheckler goes on to point out "The attachment of branches was the same as modern trees, with swelling at the branch base to form a strengthening collar and with internal layers of wood dovetailed to resist breaking," says Scheckler. "We had always thought this was modern-but it turns out that the first woody trees on earth had the same design."

While other trees quickly met extinction, Archaeopteris made up 90 percent of the forests and stayed around a very long time. With trunks up to three feet wide, the trees grew perhaps 60 to 90 feet tall. Unlike present-day trees, Archaeopteris reproduced by shedding spores instead of seeds.

Archaeopteris stretched out its branches and canopy of leaves to nourish life in the streams. The decaying trunks and leaves and the altered carbon dioxide/oxygen atmosphere abruptly changed ecosystems all over the earth.

"Its litter fed the streams and was a major factor in the evolution of freshwater fishes, whose numbers and varieties exploded in that time, and influenced the evolution of other marine ecosystems," says Scheckler. "It was the first plant to produce an extensive root system, so had a profound impact on soil chemistry. And once these ecosystem changes happened, they were changed for all time." - "Archaeopteris made the world almost a modern world in terms of ecosystems that surround us now," Scheckler concludes.

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