Carefully boring into bone to discover dinosaur blood
Fossils generally tell us about skeletons of long dead animals. Bones’ durability makes them the best candidate to become fossilized, and so that’s the starting point for most paleontological study. With the right conditions, we’ve found trace fossils, leaving impressions of softer tissues like skin, feathers or just footprints, but those are harder to come by. In the best scenarios we’ve found some mummified dinosaurs. However, a new study may turn some of this scarcity on its head, as examples of individual blood cells have been isolated inside a batch of theropod bones.
These bones were not selected because they were especially well-preserved, simply being pulled from existing museum archives. What was special was how they were examined, starting with a scanning electron microscope (the kind that make these neat images of bugs and pollen and whatnot.) Researchers found fibrous structures resembling collagen, and they found round structures that could be a great match for individual red blood cells.
Delicately digging deeper into the cell
To better identify those possible cells, an ion beam to strip off tiny layers, revealing an internal structure consistent with a blood cell’s nucleus. Mass spectrometry was then used to determine the chemical makeup of these various structures, which turned out to be a good fit for the remnants of amino acids, which are how bodies make necessary proteins. The fact that the particular amino acids that would have been in this cell are nearly identical to those found in a modern bird (in this case, an emu) further cements the idea that this really was a blood cell.
Unfortunately, specific DNA was not recoverable from the nucleus, and really nobody would have expected that, as DNA is thought to only have a shelf life of four million years, not 75 million. However, this technique is still quite exciting, as it could mean that many other fossils already in collections may have more secrets to discover if they can be reexamined. Even if actual DNA isn’t found, being able to study soft tissues like collagen, or just seeing the size and structure of blood cells, will offer lots of useful information about dinosaur physiology. It also provides evidence for the plausibility of earlier studies claiming to have found fossilized soft tissues, which had faced a fair amount of resistance when first presented.
My kindergartner said: Whoa, neat! Blood!
Source: 75 Million-Year-Old Blood Cells Discovered in Dinosaur Bones by Jon Tennant, D-brief