all species of birds have feathers & feathers are a part of a bird ->  feathers are a characteristic of all birds  feathers are not a part of reptiles & feathers are not part of mammals ->  feathers are not part of mammals or reptiles  feathers are not part of mammals or reptiles & mammals and reptiles and amphibians and birds are vertebrates0 ->  feathers are not part of mammals or reptiles or amphibians  feathers are not part of mammals or reptiles or amphibians & mammals and reptiles and amphibians and birds are vertebrates ->  feathers are not part of any vertebrate except birds  feathers are a characteristic of all birds & feathers are not part of any vertebrate except birds ->  feathers are a characteristic all of birds and feathers are not a part of any other vertebrate  feathers are a characteristic all of birds and feathers are not a part of any other vertebrate & if something is a characteristic of only one kind of thing then that something is a distinguishing characteristic ->  feathers are a distinguishing characteristic of birds  all species of birds have wings & wings are a part of a bird ->  wings are a part of all birds  mammals and reptiles and amphibians and birds are vertebrates1 & most species mammals do not have wings ->  wings are not a part of most mammals  wings are a part of all birds & wings are not a part of most mammals ->  wings are usually a part of birds  wings are usually a part of birds & mammals and reptiles and amphibians and birds are vertebrates2 -> feathers are a characteristic of all birds0: wings are usually a characteristic of birds  feathers are a characteristic of all birds0 & feathers are a distinguishing characteristic of birds -> feathers and wings together are distinguishing characteristics of birds