The fossils reveal a 300-million-year-old forest that bears little resemblance to most wooded areas today. Trees in the ancient forest sported few branches and were veiled with only scattered leaves, allowing plenty of sunlight to filter down from the forest canopy.
"The climate was ever wet, hot, and humid," said Scott D. Elrick, geologist with the Illinois State Geological Survey (ISGS).
The forest's animal life was also unlike any found today. Early amphibians, dragonflies the size of seagulls, and nine-foot-long (three-meter-long) millipedes roamed the now lost world, the scientists said.