In a message dated 95-12-01 02:23:47 EST, ornstn@inforamp.net (Ronald Orenstein) writes: >Catch-22, George! If protobirds became arboreal to escape predators, then >we have to assume that the predators, or at least some of them, could not >follow - otherwise why bother? But if this WAS effective, why fly? > > Not Catch-22: Red Queen hypothesis.