[tpanther]

The premise was that an intermediate form between a full flipper and a full leg would be useless. A seals front limbs are most certainly intermediate between a flipper and a leg, and it is not useless at all.

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Pretty useless when it comes to escaping polar bears on ice, breaking open shells or holding their young...

And lemme guess, now all we gotta do is wait millions of years to see what you’re seeing.

[allmendream]

A seal escapes predators by swimming, making its legs perfectly adapted to getting to the ice and then swimming under it. Seals break things open with their teeth, and they don't need to hold their young as their young can swim and walk just fine.

An intermediate form is obviously not useless, making the idea that the transition from a full leg to a full flipper would involve a useless intermediate absolute hogwash.