Dave Hone

Early Ornithomimosaurs don't have this.

The Oviraptorosaurs, the early ones, don't have this.

And the later ones acquire it.

And a couple of other groups as well.

And it's about making the foot stable.

And what that really does is make the foot energy efficient.

So you can imagine as an animal, you know, we have some cartilage and we've got some ligaments and tendons joining all the bones together and holding joints stable.

When you push down, that's going to compress them to a little degree.

And when you lift that weight off, they're actually going to spring back.

You're going to get a tiny little energy return.

It's the idea of those aerosols they put in all the trainers and stuff in the 90s.

It's that same principle.

And you will.

You'll get a little bit of energy return.

But of course...

Big force, particularly for a big, heavy animal, it's going to take the kind of path of least resistance.

And so if your bones are all kind of loose in the foot, what they're going to do is they're going to tend to splay out and you're actually going to lose that energy.

But if you lock the feet together, the bones can't move.

And instead, that's going to further compress those soft tissue bits and give you a bit more spring.

It makes you more efficient.