Fossil trees are the preserved remains of ancient trees that have undergone a process called fossilization. This occurs when the organic material of the tree is replaced by minerals over millions of years, turning it into stone. Fossil trees can provide valuable information about past climates and ecosystems, as they often reveal the types of vegetation that existed in different geological periods. One famous example of fossil trees is the Petrified Forest National Park in Arizona, where visitors can see large sections of ancient trees that have turned to stone. These fossilized remains date back to the late Triassic period, around 225 million years ago, showcasing the diversity of life that once thrived on Earth.