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How did birds get their wings?

How many fingers do you have? Hopefully, 5. Do you think that’s the normal condition for all animals? Do you think that’s air you’re breathing right now? … OK, so I watched the Matrix last night, but still, do you think all tetrapods (dudes with 4 feet, including you, and anything else with four flippers, wings, or feet) have 5 digits on each limb? Actually, there’s a pattern within tetrapods of limb reduction in various lineages – our earliest ancestors seemed to experiment with digit numbers and went a bit berserk by growing extra fingers from their fishy flippers.

Some early tetrapod limb bone patterns

Some early tetrapod limb bone patterns

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