A specimen of hip bone from a Tyrannosaurus rex, excavated from a ranch in Wyoming over 100 years ago, and thought to be 65 million years old is shown, by scanning electron microscopy, to have intact, mummified microscopic collagen fibers and other ultrastructural features within compact bone. Bone Haversian canals as well as lacunae and canaliculi are well preserved. Networks of collagen fibers remain intact within lacunae and what may be mummified osteocytes are shown to be present. Twenty-year-old, similarly fractured natural human hip bone shows comparable patterns of canals, collagen networks and cells, including crenated erythrocytes. Hip bone from "Moab man," human remains collected from Utah and thought to be less than 200 years old, contains no such soft tissue features within compact bone. Moab man specimens appear cleanly stripped of soft tissues and harbor burrowing insect remains. These data call into question the long ages ascribed to these dinosaur fossils and support their rapid preservation in the absence of decomposers. The high level of ultrastructural preservation also implies that these dinosaur bones are simply not very old.