But I was wondering if you could first talk about the ground up versus trees down theory, just to kind of get some background on bird flight

evolution.

Okay, so with the ground up and the trees down, none of what we've done is saying that the trees down or ground up are wrong.

But what we're saying is we've tested a mechanism that we actually observe in modern birds.

So the basic idea is that the trees down is the idea that this proto bird is in the trees and it wants to get from point A to point B so it sort of jumps and has a controlled fall, it glides down and over time it adds in flaps and all of a sudden it's flying.

The ground up is the idea that you've got, there's many many versions of it but The proto-bird is running along, this sort of little feathery dinosaur is running along, and it's using its arms to try and catch its prey.

And the motion of sweeping its arms, imagine the velociraptors in Jurassic Park.

And again, in terms of this evolving flight, so if you look at these seven metres per second, more modern but would see you know i think for the cross is at 2.2 meters per second so that is indicative also of the kind of barn door wing that the archaeopteryx really had at the time so so it wasn't quite there yet but but this would have been a way to get there