In a recent study, a team of scientists have tried to determine what the DNA of dinosaurs might have been like. The researchers were in search of genetic clues showing how the reptiles were able to take over the planet for 180 million years. The team didn't reconstruct dinosaur DNA (no Jurassic Park, I’m afraid), but instead worked backward from the closest modern-day relatives of dinosaurs.
As reported in Nature Communications, the team used a mathematical model to work out what the ancestor of birds and turtles was like genetically. This common ancestor lived 260 million years ago, 20 million years before dinosaurs first emerged. The team was able to trace what chromosome pairs were already in place in this extinct species.
"The fossil evidence and now our evidence reinforces the idea that rather than birds and dinosaurs being distant relatives, they are one in the same. The birds around us today are dinosaurs," lead author Dr Rebecca O’Connor, from the University of Kent, told BBC News.
The team estimates that dinosaurs likely had 80 chromosomes (humans have 46 by comparison). In a press release, the team argues that having lots of chromosomes may explain the diversity of birds we see, and this could apply to dinosaurs as well.
"We think it generates variation," senior Professor Darren Griffin said. "Having a lot of chromosomes enables dinosaurs to shuffle their genes around much more than other types of animals. This shuffling means that dinosaurs can evolve more quickly and so help them survive so long as the planet changed."
The finding suggests that the number of chromosomes in these ancestral creatures have not changed much in modern birds. What really changed is the information within each chromosome. Chromosomes are DNA molecules that contain all the genes that make a species.
The team argues that the full genome (the whole 80 chromosomes) is a highly stable configuration and the different dinosaur species, from the T-rex to the extinct terror birds to the common pigeon, are due to changes in the genes. The genome of a T-rex or a velociraptor would have been very different from the one of a chicken at first glance.
[H/T: BBC News]