Dinosaurs became extinct 65 million years ago following a giant asteroid impact. All except birds, that is, which are descendant of the very small dinosaurs that survived after the asteroid struck.
But what if we could recreate a real dinosaur egg? It seems as though Professor Bhart-Anjan Bhullar, a palaeontologist at Yale University, has come close to cracking it.
Bhullar has been working on the timing and mechanisms of beak evolution and, in particular, on bringing about dinosaur-like characteristics in modern birds.
In research just published in the journal Evolution, Bhullar and colleagues have created chicken embryos with dinosaur-like faces by tinkering with the molecules that build the birds' beaks.
But what did these bird ancestors look like in the first place?
"We've known for a long time what the earliest close relatives of birds looked like because the fossil Archaeopterix, the most famous example of which is in the Natural History Museum in London, was found in the mid-1800s," says Prof Bhullar.
Already covered with feathers like modern birds, they also had long tails and huge grabbing hands on their winged arms. Their heads were quite different too, because they didn't have beaks, but rather snouts filled with teeth.
An Archaeopterix fossil [Wiki Commons]
"We tried to understand what changes occur during early development in the embryo which lead to the very distinctive beak in birds versus the more ancestral reptilian snout", says Prof Bhullar.
By looking at the spatial distribution of molecules in the early embryo, which is essentially just a bag of cells, the researchers were able to link this to major changes that were caused by subtle differences in the places where genes are expressed. Instead of directly manipulating DNA, they used inhibitors to block the bird-specific part of proteins in the embryonic phase. The result? Bird embryos with dinosaur snouts rather than chicken beaks.
"In the skeleton of the snout instead of a giant bone in the middle of the face which forms the beak in birds, what we saw were two small paired rounded bones, which is what other reptiles, all mammals and all other four-legged vertebrates have, other than birds. So that was a distinctly ancestral characteristic," Prof Bhullar told us.
Very interestingly, the roof of the mouth was also transformed, indicating this one simple set of molecular changes can influence a couple of features of the skull.
The idea of creating these hybrids is certainly fascinating, but would it be ethical? The scientists terminated the embryos once they obtained their results. "To hatch animals like these, we would need to establish they could feed and wouldn't have had any major problems in their life first," says Prof Bhullar.
The major aim of the research was not, as Prof Bhullar pointed out, to resurrect a non-avian dinosaur, but to understand the major evolutionary transitions that inform the body shape of birds.
"But of course a part of me felt I had managed to create a little window back in time. The idea that in the bird embryo is the potential to revert to ancient forms... that was something really compelling,” he says.
You can listen back to the full show via the podcast below:Words: Anthea Lacchia