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Evolution of Flight in Birds

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Archaeopteryx has very similar skeletal structure to some smaller theropods. Three fingered forelimb. Reversed toe. Bipedalism. Ancestry: Thecodont ... – PowerPoint PPT presentation

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Title: Evolution of Flight in Birds


1
Evolution of Flight in Birds
  • Emily Steinmetz

2
Indroduction
  • Archaeopteryx
  • Ancestry of birds
  • Evolution of flight
  • Feathers

3
Archaeopteryx
  • First recognized in 1861
  • Appeared to be a reptile/bird intermediate
  • Believed to be an offshoot of the early avian line

www.aerospaceweb.org/ question/nature/q0201.shtml
4
Ancestry
  • Two hypotheses
  • Theropod
  • Thecodont

5
Ancestry Theropod
  • Theropods are bipedal, carnivorous dinosaurs
  • Archaeopteryx has very similar skeletal structure
    to some smaller theropods
  • Three fingered forelimb
  • Reversed toe
  • Bipedalism

6
Ancestry Thecodont
  • Thecodonts are ancestors of crocodilians,
    dinosaurs and pterosaurs
  • Ancestor of birds a quadruped
  • Long forelimbs better for wings
  • Bipedalism a result of flight

7
Flight
  • Two hypothesis
  • Cursorial (ground up)
  • Arboreal (trees down)

8
Flight Cursoreal
  • Theropod running and jumping on the ground
  • Use outstretched limbs for stabilizers
  • Fringe allowed for longer jumps
  • Lead to gliding and then powered flight

www.biology.eku.edu/ RITCHISO/554notes1.html
9
Flight Arboreal
  • Small theropod or thecodont jumping from tree to
    tree or to ground
  • Fringe would slow fall
  • Lead to gliding and then powered flight

10
Feathers
  • Initial function
  • Temperature regulation
  • Flight
  • How developed
  • Elongated scales
  • Hollow tubes

11
Feathers function (temperature)
  • Theropod covered in downy feathers
  • As moved from jumping to flying, down developed
    into flight feathers

12
Feathers function (flight)
  • Elongated scales developed along edges of limbs
  • Scales evolved into flight feathers
  • Feathers spread to streamline body

13
Feathers development (scales)
  • Scales elongated and began to be layered along a
    central vein
  • Layer became the more complex interlocking barbs
    of modern feathers

14
Feathers development (tubes)
  • Evolved similarly to stages in embryos
  • Hollow tubes gain barbs to form down feathers

15
Hypotheses (authors opinion)
  • Theropod
  • Arboreal
  • Thermoregulatory feathers
  • Tube feathers

16
References
  • Alaxander, D.E. Natures Flyers Birds, Insects,
    and the Biomechanics of Flight. Baltimore
    Johns Hopkins University Press, 2002.
  • Chatterjee, S. The Rise of Birds 225 Million
    Years of Evolution. Baltimore Johhs Hopkins
    University Press, 1997.
  • Feduccia, A. The Origin and Evolution of Birds.
    New Haven Yale University Press,1996.
  • Shipman, P. Taking Wing Archaeopteryx and the
    Evolution of Bird Flight. New York Simon and
    Schuster, 1998.
  • Zimmer, C. 2005. Dinosaurs Why do we have so
    many questions about the most successful animals
    that ever lived. Discover. 2632-39.
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