Can the presence of feathers and wings be considered a synapomorphy that triggered the adaptive radiation of birds? why or why not? can the presence of feathers and wings be considered a synapomorphy that triggered the adaptive radiation of birds? why or why not? yes, because the presence of feathers and wings before the origin of true birds is sufficient to consider these traits as a synapomorphy and a trigger of the adaptive radiation of birds. yes, because all of the true birds have feathers and wings, moreover, some tetrapods had these traits as well, so all of them can be considered as a polyphyletic group with a synapomorphy. no, because if feathers and wings existed before the origin of true birds, then these traits cannot be considered a synapomorphy for true birds because they are not unique to this group. no, because feathers and wings existed before the origin of the true birds and some of them had lost these traits, therefore true birds should be considered as a paraphyletic group.