Putting Flesh on Bone

More dinosaur bones yield traces of blood, soft tissue

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.


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FrankenChicken

How Bird Beaks Got Their Start As Dinosaur Snouts

Scientists say they have reversed a bit of bird evolution in the lab and re-created a dinosaurlike snout in developing chickens.

"In this work, we can clearly see a comeback of the characteristics which we see in some of the first birds," says Arhat Abzhanov, an evolutionary biologist at Harvard University.

The ancestors of birds are a group of dinosaurs that includes the famous velociraptor, Abzhanov says. This group of meat-eaters had long snouts, small brains and eyes, and lots of teeth. Somehow they transformed into birds, which have none of those things.

Bhart-Anjan Bhullar, another member of the research team at Yale University, says the goal is to understand exactly how birds became birds. "What's the deep history of birdiness?" wonders Bhullar. "How did the different parts of their body plan form?"

In particular, he and his colleagues are interested in birds' distinctive beak, which Bhullar calls "this insane sort of snout that they have."

To hunt for clues about the origin of the beak, the researchers have been studying various kinds of animal embryos, from birds like emus and chickens to nonbird reptiles like alligators, which are birds' closest living relatives.


Their work led them to two specific genes. These genes are active in the middle of the face-forming region of bird embryos, but not in the middle of that region in the embryos of other animals.

The team did an experiment to see what would happen if they blocked the effect of that localized gene activity in chicken embryos.

Bhullar says he remembers the night he put the altered, developing chicks under a microscope, and saw that they had unusual, broad snouts.

"That was a pretty remarkable moment," he recalls. "That's a moment that will stay with me, I think."

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