Zoo 201 evolution of birds

The flashcards below were created by user sinopa on FreezingBlue Flashcards.

  1. analagous characteristic between birds and mammals
  2. shared characteristic between birds and reptiles
    • 1 middle ear bone (stapes) (3 in mammals)
    • lower jaw: several bones (1 in mammals), articulates with quadrate
    • excrete N-wastes as uric acid (urea in mammals)
  3. Synapomorphies defining clade including bird and theropod lineages
    • bipedal
    • neck: elongate, mobile, S-shaped
    • pneumatic (hollow) bones
    • digitigrade postue
    • furcula: fused clavicles ('wish bone')
    • lunate wristbones (carpals) allow swiveling movements
  4. What is the most basal species of aeves?
    Archaeopteryx - ~450 mya
  5. therapod characteristics
    • thecodont (socketed) teeth, long tail, clawed digits on forelimbs
    • asymmetrical feathers like modern birds
    • probably capable of true flight
    • clearly shows bird/therapod relationship
  6. Neorinthes
    • clade including all modern birds
    • major radiation-Cretaceous and early Tertiary
    • 25 orders and >9900 species
    • divided into two major groups (Paleognathae (ratites) and Neoganthae)
    • no intromittent organ in most birds
  7. Neorinthes: paleognathae ("ratites")
    • ostriches, emus, cassowaries, kiwis, rheas, tinamous
    • flightless - flat sternum, poorly developed pectoral muscles
    • includes largest living bird (ostrich) up to 2.4m (8') tall & 135kg (300 lbs)
  8. Neorinthes: Neognathae
    • all other birds in 23 orders with 9800+ species
    • most with keeled sternum with strong flight muscles
    • BUT flightlessness evolved many times independently (with loss of keel, secondarily derived)
  9. Feathers
    • unique to birds
    • homologous to reptilian scales
    • epidermally derived
    • made mostly of keratin
  10. Functions of different kinds of eathers
    • thermoregulation (convervation of body heat)
    • flight (flight feathers)
    • social displays - elaborate and colorful
    • bristles around mouth of some birds-sensory function to catch insects in flight
  11. Skeletal modifications of birds
    • penumatization of bones - filled with air cavities, strong but lighter
    • skull (mass reducing speclizations for flight) - lightly built, teeth lost
  12. skeletal modifications: axial skeleton
    • specializations for flight
    • sternum with large keel (carina) - attatchment of powerful flight muscles
    • fused clavicles (furcula) - stablizing strut
  13. Endothermy, metabolism, Feeding
    • endothermic with high body temperatures (40-42C vs 36-38 for mammals) - active habit
    • high metabolic rates requrire great food intake
    • crop: storage chamber at end of esophagus that increases digestive capacity
    • gizzard: compartment of stomach grinds food with keratinized plates (replaces role of teeth)
  14. Gas exchange in birds
    • parabronchi: site of gas-exchange ('lungs'). rigid structures
    • air sacs (6-12) - poorly vascularized elastic structures
    • 1. air sacs expand/contract to ventilate parabronchi
    • 2. air flow through parabronchi unidirectional and continuous
  15. characteritics of parabronchi
    • greater gas-exchange capacity than mammal lungs
    • huge surface areas for gas-exchange
    • thinnest gas-exchange membranes among vertebrates
    • volume of air sacs several times that of parabronchial lung-makes body lighter
  16. Vision in birds
    • large eyes
    • high acuity of color vistion (active and coordinated habits)
    • retina with high density of rods and cones
  17. Mating Systems in Birds
    • 90% of birds appear to be monogamous (rare in other taxa)
    • monogomy typical in birds. both sexes equally capable of caring for young
    • DNA paternity analysis - many birds unfaithful. can result in males raising other male's young
Card Set
Zoo 201 evolution of birds
For Zoo 201, for the vertebrae portion with Lappin. Bird power point.
Show Answers