Birds

• Birds

  • Lack a urinary bladder
  • Females of most species have only one ovary
• Gonads of females and males

  • Usually small, except during breeding season when they increase in size
• Living birds

  • Toothless, an adaptation that trims the weight of the head
• Birds


  • Endothermic
  • Feathers and in some species a layer of fat provide insulation that enables birds to retain body heat
• Lungs of birds

  • Have tiny tubes leading to and from elastic air sacs that improve airflow and oxygen uptake
• Birds


  • Have color vision and excellent eyesight
  • Display very complex behaviors, particularly during breeding season, when they engage in elaborate courtship rituals
• Birds belong to the group of bipedal saurischian dinosaurs called theropods

  
• Several species of dinosaurs closely related to birds had feathers with vanes, and a wider range of species had filamentous feathers

  
• Ratites


  • Ostrich
  • Rhea
  • Kiwi
  • Cassowary
  • Emu
• Ratites

  • All flightless
• Penguins


  • Make up the flightless order Sphenisciformes
  • Have powerful pectoral muscles that they use to "fly" in the water by flapping their flipper-like wings in a manner that resembles the flight stroke of a more typical bird