So there was nothing on bird-mammal hybrids?
Because...that is totally also on this website
http://www.macroevolution.net/bird-mammal-hybrids.html#.Upo0FuI4nMo
"It is because platypuses and echidnas have many features that are typical of birds, and not of mammals, that they are classified as separate from all other mammals. Since their genomes both contain genes otherwise found only in birds, and since they have so many traits (listed in the sidebar at right) that connect them with reptiles and birds, is it not, perhaps, reasonable to consider the possibility that they are not merely birdlike mammals, but that they are actually rare examples of hybrids descended from ancient, unusual matings between mammals and birds? "
NO IT IS NOT REASONABLE