Just last week in the March 25th issue of Science, an article by Mary H. Schweitzer, Jennifer L. Wittmeyer, John R. Horner, and Jan K. Toporski announced the unimaginable. They had found soft tissue remnants inside the fossilized femur of a Tyrannosaurus Rex!
The Tyrannosaurus Rex skeleton had been found in the Hell Creek Formation in Montana a good distance from the road. The bones had to be airlifted out by helicopter. The femur bone was too big and the paleontologists were forced to break it in half. When they did, they realized that the interior did not look like fossilized bone.
Once safely in the laboratory, they demineralized the specimen and were stunned to find flexible vascular tissue that remained elastic. This vascular tissue exhibited branching patterns, and the researchers worked to show that it was not fungus or plant material. Comparison with the vasculature of demineralized ostrich bone is breathtaking with the Tyrannosaurus vessels showing nearly identical morphology to that of the ostrich.
Under a scanning electron microscope, I cannot tell the features in the dinosaur vasculature apart from those in the ostrich. Smaller structures are visble, such as osteocytes (mechanosensing cells that help modify the bone matrix) and what appear to be nuclei of endothelial cells, which line blood vessels.
I know what you are thinking…DNA.
I am sure that they are thinking it too, but even if you could find DNA, there would probably be a good number of mutations in the molecule, or you might just find pieces. Whether someday someone will be able to reconstruct a Tyrannosaurus’ DNA is anyone’s guess.
But there is another surprise. They now believe that this bone is medullary bone, which is created in female birds when their estrogen levels rise during ovulation. This was a female Tyrannosaurus Rex and she was getting ready to lay eggs!
Three other things amaze me about this find:
First, I find it very hard to believe that organic structures can last for 70 million years. Surely they are not exactly as they were, and it will be very interesting to find what types of degradation have occurred over that time period. But 70 million years is a mighty long time.
Second, it opens up entire new areas of study. Soon researchers will be cracking open fossils and looking inside. The more recent mammalian fossils have a better chance of yielding DNA and will allow us to better map out evolutionary changes. This will open avenues of research once only imagined. The more ancient Jurrasic and Triassic dinosaurs (going back some 200+ million years) have less chance of there being soft tissue and organic remains. But who knows? If this quantity of T. Rex tissue lasted this long, its half-life must be quite a bit longer.
Third, I marvel at how much has changed in science since I was young. When I was six years old, I wanted to be a paleontologist. Back then, dinosaurs were cold blooded reptiles that lumbered about slowly. Since then, we have learned that they were warm blooded. Also, we have learned that birds evolved from dinosaurs. In fact, many dinosaurs had feathers and the precursors to feathers, which are now well documented. The Tyrannosaurus Rex itself is a species that is thought to have had feathers. Now there is a sight unimagined by the dinosaur artists of my youth!