Body fossils are the preserved remains of the physical structures of ancient organisms. These can include bones, teeth, shells, and even soft tissues that have been mineralized over time. Body fossils provide valuable information about the appearance, behavior, and evolution of species that lived millions of years ago. The process of fossilization typically occurs when an organism is buried quickly after death, protecting it from decay. Over time, minerals in the surrounding sediment replace the organic material, creating a rock-like replica of the original body. This process helps scientists study extinct species and understand the history of life on Earth, including the era of the dinosaurs like Tyrannosaurus rex.