More dinosaur bones yield traces of blood, soft tissue

Science News – by Ashley Yeager

Scientists studying dinosaur evolution are finding many more bones to pick.

Researchers from London have found hints of blood and fibrous tissue in a hodgepodge of 75-million-year-old dinosaur bones. These fossils had been poorly preserved. That now suggests residues of soft tissues may be more common in dino bones than scientists had thought. Details appeared June 9 in Nature Communications.  

Scientists are excited at the idea that soft tissues might still exist in most dinosaur bones. It would give them the ability to study these long-extinct animals at the cellular level. And such studies could reveal when dinosaurs switched from being cold-blooded to warm-blooded creatures.

Matthew Collins is an expert in the study of ancient proteins at the University of York in England. (Proteins form the basis of living cells, muscle and tissues. They also do the work inside of cells.) Until now, scientists had thought that traces of soft tissue from dinosaurs remained only in really well-preserved fossils. “It’s exciting to think that we may have more soft tissue in dinosaur bones kicking around,” says Collins, who was not involved in the new study.

Susannah Maidment is a paleontologist at Imperial College London in England. She was part of a team that has just found residues of soft tissue in slivers of eight dinosaur bones. These included a toe claw from a theropod. There also was a rib from a duckbilled dinosaur. All had been found about a century ago, mostly in Alberta, Canada. Since then, the bones had been stashed in drawers at the Natural History Museum in London.

The team used a scanning electron microscope to study the bones. This special microscope can highlight features that are just a few billionths of a meter across. The dinosaur bone images revealed what appeared to be red blood cells. A second type of powerful microscope probed the structure of some bone features. These images showed bands similar to patterns formed by collagen in animal bones today. Collagen is a fibrous protein. It is found not only in bones, but also in cartilage, tendons and other connective tissues.

Chemical analyses showed the bone slices contained amino acids. These are the basic constituents of proteins. The slices also contained other molecules. Some of these molecules resembled those in the blood of an emu. Others resembled collagen from rabbit bone.

“Those results tell us that there are actual original components of blood and collagen preserved in the fossil bones,” Maidment says.

The size of a blood cell can tell scientists a lot. For example, smaller red blood cells indicate its host had a faster metabolism. (An organism’s metabolism is the set of life-sustaining chemical reactions that take place inside its cells.) Faster metabolisms are typical of warm-blooded animals.

“The ancestors of dinosaurs are thought to have been cold-blooded animals,” Maidment notes. Birds, the descendants of the dinosaurs, are warm-blooded. “This means that somewhere on the line to birds, within the dinosaur group, warm-bloodedness evolved,” she explains. “At the moment, we have no direct evidence for this transition from bones alone.”

Collins at York argues that scientists need to go beyond pointing out that amino acids and proteins exist in fossil dinosaur bones. After all, he notes, scientists have known about that since the 1970s. He says the next big advance will be extracting these preserved proteins. Doing so would allow researchers to determine the order of the amino acids in each protein. That information could help fill in the gaps in dinosaur evolution.

Preliminary studies have delivered these kind of dinosaur data. However, the results have not been reproducible, Collins says. Reproducible means another scientist should be able to recreate an experiment under the same conditions and be left with the same results. “That’s what we’re waiting for now,” Collins says.

https://www.sciencenewsforstudents.org/article/more-dinosaur-bones-yield-traces-blood-soft-tissue