primitive fish of the Mississippi valley having a long paddle-shaped snout
small densely furred aquatic monotreme of Australia and Tasmania having a broad bill and tail and webbed feet; only species in the family Ornithorhynchidae
New evidence, however, challenges that theory.The duckbill platypus, it turns out, gets about eight hours of REM shuteye a day. 新证据向上述观点提出挑战，它推翻了鸭嘴兽一天睡眠八小时的理论。
