Other Heterostracans had fused plates on their heads, with diamond-shaped or elongated scales covering their tails.

其他 Heterostracans 的头上有融合的板，尾巴上覆盖着菱形或细长的鳞片。

And heterostracans, osteostracans and placoderms have been found in both salty AND fresh water environments.

在咸水和淡水环境中都发现了 heterostracans、osteostracans 和 placoderms。

And scientists have seen signs of those changes in the armor of heterostracans, osteostracans and placoderms.

科学家们已经看到了异类动物、骨类动物和盾皮动物的盔甲发生这些变化的迹象。

They didn't have much of one -- their backbones, like those of heterostracans and earlier fish, was made of cartilage.

它们的脊椎骨并不多——它们的脊椎骨，就像杂鱼和早期鱼类的脊椎骨一样，是由软骨构成的。

So armored fish came in a variety of shapes and sizes during the Silurian and Devonian, from tiny Heterostracans to massive Placoderms.

因此，在志留纪和泥盆纪期间， 装甲鱼的形状和大小各不相同，从微小的异类鱼到巨大的盾皮鱼。

One such group was the Heterostracans, whose name means " different scales." They, too, looked like small, armored ovals with thick, fleshy tails.

Heterostracans就是这样的一个群体，其名字的意思是“不同的尺度” 。它们看起来也像小的、带铠甲的椭圆形动物，尾巴又厚又多肉。