You are encouraged to finish reading "Soft Tissue in Fossils", here. Further discussion is available in "Those Not So Dry Bones".
Ask the average layperson how he or she knows that the earth is millions or billions of years old, and that person will probably mention the dinosaurs, which nearly everybody “knows” died off 65 million years ago. A recent discovery by Dr. Mary Schweitzer, however, has given reason for all but committed evolutionists to question this assumption.
If dinosaurs lived over 65 million years ago, why do some dinosaur fossils still contain well-preserved soft tissues?Bone slices from the fossilized thigh bone (femur) of a Tyrannosaurus rex found in the Hell Creek formation of Montana were studied under the microscope by Schweitzer. To her amazement, the bone showed what appeared to be blood vessels of the type seen in bone and marrow, and these contained what appeared to be red blood cells with nuclei, typical of reptiles and birds (but not mammals). The vessels even appeared to be lined with specialized endothelial cells found in all blood vessels.