bird

16th across adapted also among anatidae aves beak become bird but century chambered characterised clade developed digestive egg eggs evolved extant feathered feathers flight flightless fly for four generally generations have heart high intelligent island laying legged less make many members metabolic moa modern more most parrots particularly penguins rate ratites recent respiratory shelled skeleton some species swim systems that the tools transmit two uniquely use warm was which winged wings with