Class Aves

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Class Aves
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Archaeopteryx
150 MYA
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Archaeopteryx Skeleton
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Avian Skeleton
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Major Bird Groups

• Paleognathae
• Mostly flightless
• Usually ratite sternum (flat)
• Neognathae
• Mostly flying birds with carinate sternum (keeled)

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Is It A Bird?

• Wings
• Feathers
• Beak
• Oviparous

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Placode Specification
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Placode Growth
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Barb Barbule Development
Down feather development Pennacous feather
development
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Mature Feather
Pennaceous
Plumulaceous
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Feathers or Scales
Inhibition of BMP4 signaling in chick hindlimb
causes dorsal scales (scutes) to develop as
feathers and prevents apoptosis of interdigit
webbing
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Does a Chicken have Lips?
Figure 1   A "hen's tooth" formed by the
combination of chick pharyngeal (presumptive jaw)
ectoderm and mouse molar mesenchyme. (From Kollar
and Fisher, 1980 courtesy of E. J. Kollar.)
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Adaptations for Flight
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Unique Pulmonary Structures
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Bird Brained
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A Bird's Eye View
Optic nerve
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Wing Forms
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Migration
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Navigation

• Birds can sense Earths magnetic field
• Orient relative to field
• Calibration of internal compass
• Twilight cues
• Nocturnal celestial cues
• Daylight cues

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Parenting
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Juvenile Forms
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Reproductive System
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Largest Bird
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Largest Flying Bird
Albatross 11ft wing-span
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Smallest Flying Bird