Paedomorphosis (juvenile characteristics remaining in adults) is a really neat mechanism for producing radically different-looking animals in a short time.
In the short span of ~30,000 years, we've managed to turn wolves into corgis that look like puppies their entire lives. We ourselves are often said to be a result of paedomorphosis from other primates -- now with less hair, bigger heads, and weaker muscles.
You can see some chang s over 100's of years. Nothing as dramatic as this. I wouldn't call 10 million years quite a blip though. But dinosaurs were around for almost 200 million years! Some animals have not evolved much in hundreds of millions of years, like sharks and crocodiles.
Island animals are often forced to evolve more quickly as a result of far more limited resources. Island animals don't often have the option to migrate to a similarly hospitable environment like mainland animals can.
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[ 3.7 ms ] story [ 31.4 ms ] threadIn the short span of ~30,000 years, we've managed to turn wolves into corgis that look like puppies their entire lives. We ourselves are often said to be a result of paedomorphosis from other primates -- now with less hair, bigger heads, and weaker muscles.
Also air with less Oygen is lighter, another good reason for Dino-birds to loose weight.