鸟类是如何在恐龙大灭绝中幸存下来的?

Tom O'Hanlon把Fay的问题交给了剑桥大学的David Norman。大卫:压倒性的证据表明，大约6600万年前，有一颗巨大的陨石撞击过地球。从某种意义上说，这次爆炸造成了一系列巨大的环境问题:大量的水蒸气，大量的化学物质被引入大气，完全扰乱了我们的生态系统。我想，就现代理论化而言，与之相当的是核冬天。就好像发生了一场核浩劫，几乎毁灭了地球上的生命，但又不完全是这样。汤姆:考虑到我们今天还活着，有些事情显然已经过去了。那么谁生谁死是否有某种规律?大卫:当然在陆地上，任何体长超过一米的生物都可能灭绝了。这可能与小型生物体的生物学性质有关。你可以说，大多数大型动物都处于食物链的顶端，也许它们更专业，也最容易受到环境干扰的影响。 That’s certainly the pattern we see in ecology today. The things that have most chance to survive are the scavengers, the small fast reproducing sorts of organisms. And, in a way, the lizards, the snakes, the small crocodiles, small mammals that were our ancestors, and various other little organisms seem to have got through because they were the most resilient to environmental disturbance. The little, insulated, feathered bird-like dinosaurs also got through and, therefore the dinosaurs did survive the extinction, but they survived because they were small bird-like creatures rather than big scary dinosaurs. Tom - I suppose we’re really grateful for today? David - I guess so, yeah. Although some of us would actually quite like to see a dinosaur in the flesh at full size. The nearest we’ll ever get to it is something like an Emu, or an Ostrich, or a Rea. They’re feet, especially with something like a Rea have those three classic taloned toes which look very, very reptilian and wouldn’t be so ; different, except in scale, from something like the feet of a dinosaur like T. Rex. Tom - There you go Fay. I hope that managed to meteor your expectations.

下周我们将讨论大卫的问题。大卫:如果我们把一面镜子放在50万光年之外，反射出地球，我们能看到地球一百万年前的样子吗?