Unfortunately, Jarvik refused to let anyone study his tetrapod.

不幸的是，贾维克不让别人插手他的研究工作。

Whatcheeria was an early tetrapod, as the first land animals with backbones were known.

瓦切螈是一种早期的四足动物，作为第一批有脊椎的陆地动物而为人所知。

And the situation is very different with other four-legged animals, tetrapods.

这种情况与其它四足动物有非常大的不同。

Today three early tetrapods are known and none has five digits.

今天，已经知道早期有三种四足动物，但没有一种跟数字5有关系。

This was the missing link between bony fishes and tetrapods, including human beings, so this was a fantastic expectation.

这是硬骨鱼和包括人类在内的四足动物之间缺失的一环，所以对我们来说这种期待很奇妙。

Unlike many early tetrapods, bones of Whatcheeria have been discovered from different points in the animal's life.

与许多早期四足动物不同的是，人们发现了瓦切螈不同生命阶段的骨骼。

Your few four-legged ancestors, the tetrapods, struggled in tropical river plains.

你的少数四足祖先， 四足动物，在热带河流平原上挣扎。

One of the earliest of these new creatures was a tetrapod named Acanthostega.

这些新生物中最早的一种 是一种名为棘螈的四足动物。

But, the earliest tetrapods were all carnivorous predators.

但是，最早的四足动物都是肉食性 捕食者。

It was a huge boost for adventurous tetrapods that were colonizing dry land.

这对在陆地上定居的冒险四足动物来说是一个巨大的推动力。

But the bigger news was a major change among the tetrapods.

但更大的消息是 四足动物发生了重大变化。

These were creatures like Edaphosaurus, one of the earliest known tetrapod herbivores.

这些是像Edaphosaurus这样的生物， 它是已知最早的四足草食动物之一。

These arid wastelands would’ve been uninhabitable for early tetrapods, but not for the amniotes.

这些干旱的荒地 对于早期的四足动物来说是不适宜居住的，但对于羊膜动物来说却不是。

And lungfish, being related to the ancestors of all tetrapods, or four-limbed vertebrates, are equipped with true lungs.

而与所有四足动物或四肢脊椎动物的祖先有关的肺鱼，都配备了真肺。

And a new way of breathing wasn’t the only thing tetrapods would need.

一种新的呼吸方式并不是 四足动物唯一需要的。

But about 385 million years ago, in the Devonian Period, tetrapods started venturing away from the water's edge.

但大约 3.85 亿年前， 在泥盆纪时期，四足动物开始冒险离开水边。

What’s clear is that these tetrapods were walking on all fours, not paddling or flopping.

很明显，这些四足动物是四足行走，而不是划桨或翻滚。

In fact, scientists think they walk like the ancestors of all tetrapods might have walked – 'fishapods', if you will.

事实上，科学家们认为它们的行走方式与所有四足动物的祖先可能行走的方式一样——“鱼足类”，如果你愿意的话。

In particular they sought lobe-finned fish of the type that presumably were ancestral to us and all other walking creatures, known as tetrapods.

据推测，那种鱼是所谓的四足动物，即我们和其他所有会行走的动物的祖先。

But in order to become truly terrestrial, tetrapods had to be able to keep their embryos wet on dry land.

但为了成为真正的陆生动物，四足动物必须能够让它们的胚胎在干燥的土地上保持湿润。