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t1_jb7ptv0 wrote

The terrestrial version are called Tetrapods (literally "four feet"), which originated about 350 million years ago, with modern descendants being amphibians, reptiles, birds, and mammals (though some have subsequently lost tails like us, or feet like snakes).

However, these limbs are just modifications of pectoral and pelvic fins of our fishy ancestors. The true origin of this body plan is 435 million years ago, with gnathostomes, the jawed vertebrates. This is the origin of the two pairs of fins, which eventually became limbs.

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