From cell details of slices of trunks, Meyer-Berthaud was able to show that these ancient trees also had lateral buds on their trunks and branches. "This was unique to Archaeopteris," says Scheckler. "It was the only plant at that time that could bud and continue growing after the main axis tip died; although seed plants now have that ability."

"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 this exact same design."

Another unique feature of Archaeopteris while it dominated ancient forests was its long-life. Archaeopteris was the first long-lived perennial. "Other plants ran out of ability to grow," says Scheckler. These trees could grow for 10-50 (100) years or more. They had no apparent life span."

Some of the trees that Meyer-Berthaud and Scheckler found were possibly 40- to 50-years-old when they fell into the sea some 350 million years ago. There are differences between Archaeopteris and modern trees, Scheckler points out. Archaeopteris reproduced by releasing spores rather than by producing seeds. That is one of the reasons why paleobotanists suspect that today's trees come from a sister line of plants, the "progymnosperms." Archaeopteris is more like an ancient aunt than a direct ancestor, but became extinct within a short period of time at the end of the Devonian age.

Before they left, though, Archaeopteris trees changed the world, Scheckler reports.

The earth's atmosphere was changing rapidly, going from perhaps 10 percent to 1 percent CO2 and from about 5 percent to 20 percent oxygen over a 50-million year period in the (late) Devonian period. All plants were responsible fo
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Contact: Stephen E. Scheckler
stephen@vt.edu
540-231-6653
Virginia Tech
22-Apr-1999