Animals

80-Million-Year-Old Dinosaur Blood Vessels Never Fossilized

The tiny, delicate vessels that carried blood through a duck-billed dinosaur 80 million years ago still contain the beast's tissue, a new study finds.

Tiny, delicate vessels that carried blood through a duck-billed dinosaur 80 million years ago never fossilized and still contain the beast's tissue, a new study finds.

Researchers discovered the prize specimens on the femur (leg bone) of Brachylophosaurus canadensis, a 30-foot-long (9 meters) duck-billed dinosaur that was excavated in Montana in 2007. But it wasn't immediately clear whether the blood vessels were made of organic matter originally from the dinosaur, or whether they had been contaminated over the years and were now made of bacteria or other components.

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Now, several tests show that the specimens are the original blood vessels, making them the oldest blood vessels on record to survive with their original components, the researchers said. [Images: Discovering a Duck-Billed Dinosaur Baby]

The finding adds support to a growing pile of evidence that organic structures such as blood vessels and cells can persist for millions of years without fossilizing, they said. In fact, the blood vessels are only the latest part of the B. canadensis fossils the group is examining.

"The other major components of the bone from this dinosaur (bone matrix and bone cells) had already been studied, so we began studying the blood vessels in isolation," study lead researcher Tim Cleland, a postdoctoral researcher of chemistry at the University of Texas at Austin, told Live Science in an email.

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The new project allowed the researchers "to focus on the vascular proteins that may hold more evolutionary information," said Cleland, who started the research while studying molecular paleontology at North Carolina State University.

To study the blood vessels, Cleland demineralized a piece of the leg bone and studied it with high-resolution mass spectroscopy. This technique uses an instrument to weigh and sequence proteins and peptides (chains of amino acids that are like proteins, but shorter). One of the proteins within the vessel, myosin, is found in smooth muscles found in the walls of blood vessels, the researchers said.

In a separate test, they used antibodies to detect specific proteins in a thin slice of the blood vessels. The antibodies revealed the same proteins that the mass spectroscopy did, thus confirming the results.

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The researchers also tested the bones of chickens and ostriches, both of which are living relatives of dinosaurs. In both the modern and ancient samples, the peptide sequences were the same as those found in blood vessels, the scientists said.

"This study is the first direct analysis of blood vessels from an extinct organism, and provides us with an opportunity to understand what kinds of proteins and tissues can persist and how they change during fossilization," Cleland said in a statement. "This will provide new avenues for pursuing questions regarding the evolutionary relationships of extinct organisms, and will identify significant protein modifications and when they might have arisen in these lineages."

Now that researchers have sequenced a large number of bird and crocodilian genomes, there should be more information about the proteins made by these creatures. This data may, in turn, help researchers study dinosaur proteins that have survived over millions of years, Cleland said.

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"Part of the value of this research is that it gives us insight into how proteins can modify and change over 80 million years," Mary Schweitzer, a molecular paleontologist at North Carolina State University and co-author of the paper, said in the statement. "It tells us not only about how tissues preserve over time, but gives us the possibility of looking at how these animals adapted to their environment while they were alive."

The results were published online Nov. 23 in the Journal of Proteome Research.

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Shown are the approximately 80-million-year-old blood vessels belonging to a duck-billed dinosaur.

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.

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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.

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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."

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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.

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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.

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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

T. rex

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."