Dinosaur Blood and Bone Cells Found: Photos
Red blood cells and collagen fibers from bone are preserved in 75-million-year-old dinosaur bones.
Red blood cells and bone collagen fibers have just been recovered from 75-million-year-old dinosaur fossils. The findings, published in the journal Nature Communications, suggest that organic protein molecules remain intact for far longer than anyone had ever imagined. "We have several indications that the structures we found are consistent with red blood cells and collagen," lead author Sergio Bertazzo of Imperial College London's Department of Materials told Discovery News. The term "organic" in this instance is used in reference to a material, mainly composed of carbon, which is not the mineral present in the fossil.
For the study, the scientists applied extremely high magnification from electron microscopy and a tool called a "focused ion beam" to probe the fossils. The remains came from eight dinosaur bones that were not particularly well preserved. Some of the remains belonged to Chasmosaurus, a plant-eating, four-legged dinosaur with a head frill and horns.
Meat-eating dinosaurs were studied too, such as this claw from a carnivorous dinosaur that once roamed what is now Alberta, Canada. So far, the researchers have not detected DNA in the discovered cells. "We have found no evidence for DNA in the red blood cells we have found," co-author Susannah Maidment of Imperial College London's Department of Earth Science and Engineering told Discovery News. She added, "I think it would be unwise to say, "No, we'll never find DNA," because who knows what we might find in the future? Increasingly, studies like ours are showing that original components can be preserved in fossils. So maybe."
Prior research concluded that protein molecules decay in relatively short periods of time and cannot be preserved for longer than 4 million years. The new study clearly challenges that theory. What's more, the fossils the researchers studied were only in average condition, not having been pristinely preserved. Fossils such as the ones studied by Bertazzo in this image, and the ones museum goers see on display, could therefore still retain preserved organic remains too. In short, the presence of cells from soft tissues in dinosaur fossils could be much more common than previously thought.
The size, arrangement and structure of the fibers seen in this image -- taken of one of the dinosaur fossils -- are consistent with collagen from bone, according to the researchers. Collagen is the main structural protein found in animal connective tissues. Mature bone (and in this case, that's an understatement!) is composed of proteins and minerals. Approximately 30 percent of any bone is composed of organic compounds, of which 90–95 percent is collagen.
Most of the fossils studied by the scientists came from lower body parts, such as ribs and toe bones, and not the head area. This skull, held by Maidment, is a lasting reminder of what one of the dinosaurs looked like, however. The researchers took care to determine that the preserved cells did not come from another more modern species. The discovered red blood cells were comparable to those of living birds, such as emus, which the scientists also studied for comparison. Like the detected dino cells, "bird red blood cells are also oval and contain nuclei," Bertazzo explained, adding that "mammals are the only animals whose red blood cells do not contain nuclei, thus we can rule out contamination from a human." He continued, "The main difference between the dinosaur cells and those of birds is that the dinosaur cells seem to be quite a bit smaller. However, this is not surprising since they have been buried for 75 million years and have likely shrunk." He further added that blood cells size is extremely variable within different species.
This photo includes notes on the bottom, showing just some of the techniques the researchers employed in order to see and understand the fossils' internal composition. The green coloration corresponds to denser materials, while the red coloration picks up less dense materials, including the identified cells. Mary Higby Schweitzer is a paleontologist at North Carolina State University who is famous for leading teams that previously discovered blood cells in dinosaur fossils. She also later discovered soft tissue remains in
fossils. Schweitzer told Discovery News that the new findings confirm "our own contention that this type of preservation is more common than previously allowed, and that we should put a lot more effort into mining fossils for the information they contain." She continued that the paper is important "in showing what happens when you really look at ancient bone and are not bound by the expectation that nothing could possibly persist." Higby Schweitzer concluded, "If you don't look, you won't find. But if you do, you never know."
There is now tremendous hope that continued research on organic material in dinosaur fossils could lead to a better understanding of these still mysterious prehistoric animals. Maidment said, "The next questions we need to answer are how and why are these cells preserved, how far back in time does this style of preservation extend, and is it restricted to particular rock types and burial environments, or is it widespread in the geological record?" Ongoing mysteries that could be solved include resolving the debate on whether or not dinosaurs were warm or cold-blooded. It's even possible that some dinosaurs were ectothermic (cold blooded) while others evolved to become endothermic later, since today's birds are warm blooded. Bertazzo said, "If we could find red blood cells in many different types of dinosaurs, we might be able to look at the range of cell sizes and establish which dinosaurs had the fastest metabolism."