Biologist Arkhat Abzhanov on Archosaurs, paedomorphosis, and the evolution of birds
How do birds relate to dinosaurs? How can we trace the evolution of birds? Associate Professor of Organismic & Evolutionary Biology at Harvard University Arkhat Abzhanov speaks on discovering evolutionary connections between different groups of organisms.
The class Aves is one of the most successful groups of animals on our planet: there are over ten thousand species, there are dozens of families and orders of these animals, they can be found anywhere on the planet, they can be found in the water, under the surface, above the surface. They are capable of powered flight; there are two groups of vertebrates which are capable of powered flight. And they are extremely successful.
In order to understand the evolution of Archosauria we wanted to trace the changes in the skulls of these animals all the way from the beginning, from primitive Archosaurs all the way to birds. And this work involved close collaboration with some important paleontologists including Dr. Mark Norell from the American Museum of Natural History. He is actually concerned to be number one dinosaur guide and even more importantly he has a wonderful collection in his museum of dinosaur eggs, he was the first to discover dinosaur theropod eggs in Mongolia and many of those eggs contained fossilized embryos. And this will become very important for our work, being able to understand the genetic changes, which happened in the dinosaurs will be quite critical for explaining the evolution of the birds.
We can show that using morphometric analysis of skulls the birds are highly paedomorphic versions. That is very juvenile versions of their ancestors, the theropod dinosaurs. They have very baby like skulls. And what we are trying to do now, we are trying to understand some of the molecular developmental mechanisms of how that change is actually possible.