In a message dated 8/25/01 10:16:43 AM EST, jbois@umd5.umd.edu writes: << An enduring mystery is: why didn't dinos reevolve? >> They did. We call them phorusrachids, ostriches, emus, moas, elephant birds, diatrymids, etc. These are exact Cenozoic analogues of what people usually call theropod dinosaurs in the Mesozoic. There is no mystery.