In “Oldest Known Wood” (The Scientist , August 11, 2011) Jef Akst reports that “Two newly described fossils suggest that wood is some 10 million years older than previous believed” (No kidding!):
… two relatively small fossils provide new clues, and suggest that wood evolved at least 10 million years earlier than previously documented, according to a study published today (August 11) in Science.
One fossils is 407 million years old and the other 397 million years old, give or take a few million.
See also: Live birth in lizards developed earlier than thought