Dr Berry described the discovery as a "spectacular" find.
The upright stumps of fossilised trees were first uncovered after a flash flood in Gilboa, New York, more than a century ago.
But until two further fossils were found two years ago, which had fallen sideways with their trunk, branches, twigs and crown still intact, no-one knew what the entire trees looked like.
The American team called in Dr Berry, who has 17 years of tree fossil expertise, to help.
Dr Berry, of Cardiff university's School of Earth, Ocean and Planetary Sciences, said it was a "spectacular find" which had allowed scientists to recreate early forest ecosystems.
"This was also a significant moment in the history of the planet," he said.
Fossil of 385 million year old tree found in New York
Posted on Monday, Apr 23 2007 @ 02:35 CEST by Thomas De Maesschalck