What does the divergence timeline suggest about the kiwi ancestors before they lost flight?
Answer
They were flying birds that colonized the landmass before it fully separated
The genetic evidence linking kiwi to the distant elephant birds, coupled with the geological timeline of Gondwana breakup (roughly 85 million years ago), strongly implies that the ancestors of the kiwi were capable of flight. They must have undertaken a dispersal event, landing safely on the landmass destined to become New Zealand, or established themselves there before the island separated substantially from larger continents. Once isolated in a predator-free environment, the advantage of flight diminished to zero, leading over deep time to the complete loss of that capacity and the evolution into their current terrestrial form.
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