Via SciNews:
... At the discovered site, located near Wuda in Inner Mongolia, China, the plants were preserved as they fell, in many cases in the exact locations where they grew, because volcanic ash covered them over the course of only a few days.
“It’s marvelously preserved,” said Hermann Pfefferkorn, a Professor at the University of Pennsylvania and a co-author on the study. “We can stand there and find a branch with the leaves attached, and then we find the next branch and the next branch and the next branch. And then we find the stump from the same tree. That’s really exciting.”
The researchers date the ash layer to approximately 298 million years ago that falls at the beginning of Permian, during which Earth’s continental plates were still moving toward each other to form the supercontinent Pangea.
The researchers also found some smaller trees with leaves, branches, trunk and cones intact, preserved in their entirety. They were able to examine a total of 1,000 m2 of the ash layer in three different sites located near one another....
This news was also explained in the Science Magazine's podcast. Good Listening!
And the published paper from PNAS (hat tip - Don B.)