英语听力：恐龙是怎样炼成的—14

-If I bring a bone over, we can superimpose these two. It's got one big muscle attachment right here and the dinosaurs have a muscle scar just like this. It appears in the first bipedal dinosaurs, this scar on the outside of the fibula and it is not present in earlier animals. So this is another link between dinosaurs and birds.-So I must look for that the next time I see …

-Yeah, you can see that. T-rexes have a huge one of those, a massive scar like this big.

By estimating the muscle sizes of extinct animals and inputting them into computer models, John is able to get an incredible new insight into how dinosaurs actually moved.

-It's basically running a simulation. The computer’s figuring out what is the best way to use these muscles, given what we’ve put in to raise the body up. We are not animating it. And we are not saying, “Do it this way.” We are just giving it some basic rules of biology. This is what kinds of things you should be trying to do overall and let it find the best solution.

-Yeah. So John you've actually done right, trying to reconstruct how T-rex would have looked, how its muscles would have worked, how he would have run. What kind of results have you got from that?

-Yes. So we found using our computer models that human sprinters which can do 25 miles an hour or a little faster would probably be pretty well matched for a muscular tyrannosaurus or an average human who can run about 15 miles per hour would probably be a pretty good match for a kind of skinnier version of a T-rex.

-John, I’ve heard some theories where T-rex has been put forward as running very fast, probably faster than that. So has your work basically disapproved that?

-I think it's put a lot of doubt in that idea that a T-rex could run like as fast as a race horse, or even faster, like forty miles an hour, something like that. I don't think you’ll need an automobile to outrun a T-rex.

-We do have a chance of outrunning them, running away.

-Never gonna happen, thankfully.

The work of scientists like John has allowed us to not only refine our ideas about these extinct animals, but has actually transformed our image of them. If you think about tyrannosaurus, T-rexes for example, we used to think of him as standing upright like gorilla, but now we know he couldn't have worked like that. You treat him like an engineering problem, in format, using comparative anatomy of living animals. And how we know that his body was much more horizontal with his tail held up in the air, and our reconstructions are much morerobust. We are getting as close as we possibly can to what this long-dead animal would have looked like.