Animal Biology
Professor Chris Gillen
Weekly assignment 12
WA12: Two hypotheses regarding the origin of flight in the early ancestors of modern birds are the "trees down" and the "ground up" hypotheses. Describe generally the different categories of experimental evidence that might resolve this question.
In the trees down hypothesis, flight originates as gliding in animals that gained altitude by climbing trees.
In the ground up hypothesis, flight originates in animals that flapped forearms as they ran along the ground (perhaps
to catch insects).
Answers should be about 1 typed page in length.