这些鸟是人所共知的因为它们的大声咯咯的叫，四个-有趾的脚，和灿烂的羽毛。
These birds are best known for their loud cackles, four-toed feet, and brilliant plumage.
鸸鹋是一种大型的澳大利亚不会飞的鸟，类似于鸵鸟，但是有三趾的脚和灰色或棕色的羽毛。
Emu is a large Australian flightless bird, similar to the ostrich but with three-toed feet and grey or brown plumage.
例如，四趾的始祖鸟先于三趾的始祖鸟出现，但北美的化石证据表明，这两种动物之间有一个急促而不均衡的转换过程。
The four-toed Eohippus preceded the three-toed Miohippus, for example, but North American fossil evidence suggests a jerky, uneven transition between the two.
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