An ancient forest revealed
In the Khamkeut District of central Laos, silica-rich groundwater and time have performed a remarkable act of preservation. Massive stone logs, the fossilized remains of an ancient tropical forest, lie embedded in the ground. These are petrified trees; they are some of the oldest direct evidence for the kind of tropical hardwood forests that define Southeast Asia today. Their discovery fundamentally alters the timeline for the evolution of this ecosystem. Prior to this find, the primary evidence for ancient forests came from the study of fossilized pollen, known as palynology. While useful, pollen records have limitations. The fossil wood of Khamkeut provides a much more direct and detailed picture of the forest's structure and composition.
The trees belong to the Pliocene epoch, which lasted from 5.3 to 2.6 million years ago. Analysis of the wood's cellular structure identified it as belonging to the family Dipterocarpaceae. This family of towering hardwood trees dominates modern Southeast Asian rainforests and is ecologically and economically significant. Finding such well-preserved examples from the Pliocene confirms that these famous trees have been a defining feature of the region's environment for millions of years, far longer than the pollen record alone could prove. The fossils show that a forest with a similar floristic composition to present-day forests in the area existed at least since the Pliocene.