Most fossils contain preserved an organism's hard tissues, shell, bone, and such; but encountering actual soft tissue, containing cells and proteins, is rare and practically unheard of.
In 1990, paleontologist Dr. Mary Schweitzer of Montana State University and a group of scientists uncovered soft bone tissues from the thigh of a 65 million year old Tyrannosaurus Rex named MOR 1125. This T-Rex was found in a sandstone formation in Montana, and was 18 years old when it died. The tissues included blood vessels, cells, and proteins which affect bone formation. The blood vessels which the soft tissue contained, when squeezed, secreted a reddish liquid substance which possessed both the shape of red corpuscles under the microscope and magnetic attraction due to iron. Red blood cells contain dinosaur DNA the blueprint for life featured in the fictional recreation in the book and film Jurassic Park. This has been the only sample of preserved soft tissues ever recovered from a dinosaur.
The discovery of the soft bone tissue was made when the large femur bone was needed to be broken to enable it to be lifted by a helicopter. After the bone was broken, the inside of the femur revealed the tissue inside. Schweitzer suddenly smelled rotting flesh, which aroused her scientific curiosity.
These findings might provide new insights into dinosaur evolution, physiology, and biochemistry, such as diet, sexual maturity, and whether the specimen is male or female. Finding these tissue samples changes the way scientists think about fossilization, and may increase their understanding of extinct life.
The excavation of the Tyrannosaurus Rex took about three years, and was carried out by scientists from the Museum of the Rockies in Bozeman, Montana. Schweitzer performed a number of tests on the fossils that are common medical practices today. The paleontologist and her colleagues removed mineral fragments from the interior of the femur by soaking it in weak acid. The fossil dissolved, exposing a flexible, stretchy material and transparent vessels.
Further chemical and biological analysis into soft tissue of the Tyrannosaurus Rex may allow scientists to answer questions about the physiology of dinosaurs were they warm-blooded, cold-blooded, or somewhere in between? is an example.
Perhaps scientists will be motivated by this finding to retain fossils for future cellular and molecular testing.