The probability that an organism will become a fossil is rare. The critters of long ago, could not go to a Paleo-Photo Shop to take pictures to record their ancestry. So we don’t have an actual record, just old body parts!

Fossils may record direct or indirect evidence about their past life. Direct fossil evidence is any remaining part of an ancient organism. Direct evidence includes the preserved or altered hard parts of organisms, such as bones or shells. Preserved soft tissues, for example skin or feathers, are also a type of direct evidence. Indirect evidence is information about how ancient life lived. It includes such things as the footprints of ancient animals, or even coprolites (fossilized dung)! 

Bone fragment is direct evidence