Bird%20Evolution%20and%20Classification

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Bird Evolution and Classification

• Dr. Girish Jathar
• Scientist-in-charge
• ENVIS Centre
• BNHS

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What are birds?

• Bipedal
• Feathers (diagnostic)
• Insulation
• Lift and thrust
• Toothless bills covered with horny sheath
• Wings
• Ability to fly
• Egg laying and Parental Care
• Warm Blooded

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Characteristics (cont.)

• Adaptations associated with flight
• Skeleton
• Musculature
• Physiology
• Reproductive system
• Central Nervous System

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Other features?

• Nucleated RBCs
• Scales on legs
• Ankle in tarsal bones (not between long bones and
  tarsals)
• Bipedal (theropods)
• Yolked, polar, cleidoic egg
• Females are heterogametic - Female WZ Chromosomes
  and Male ZZ chromosomes

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Evolution of Birds
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Link Between Birds and Reptiles

• Lots of morphological, behavioral and
  physiological similarity between Reptiles and
  Birds. Archaeopteryx lithographica

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Founding of Archaeopteryx

• Lithograph Quarrymen Jurassic limestone
• Single feather impression 1861, Bavarian Quarry
• Complete skeletal impression Few months later
• 2nd complete skeleton 1877, quarry near
  Eichstatt, Germany
• Herman von Meyer
• Archaeopteryx lithographica

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Archaeopteryx

• Debates
• Support of Darwinian evolution
• Darwin predicted transitional fossils in 1859
• one of the best links between two taxa
  (Feduccia, Ostrom, etc.)
• Creation / Evolution debate
• Evolution of feathers (flight or insulation
  first?)
• Evolution of homeothermy in birds
• Evolution of flight
• Ground-up vs. Trees down

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Could it fly?
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The historical evolution of flight debate

• Two main hypotheses
• Ground-up (cursorial hypothesis)
• Trees-down (arboreal hypothesis)

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Ground-up

• Assume biped, cursorial ancestor
• Has to be bipedal to use wings at all
• Large legs for running muscle attachment
• Bones of legs are long
• Once running
• Use feathers for other things
• Catch insects
• Pick up minimum speed for lift Flight

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Trees-down

• Assume semi-bipedal leaping and gliding ancestor
• Use of claws to scale trees, then glide to ground
• Claws retained in winged appendages
• Short hand wing (power), relatively long arm wing
  (lift)
• Claw geometry (Feduccias study)
• Large attachment sites for downstroke on humerus
  but no keeled sternum
• Flying squirrels?

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Winner?

• Trees-downmaybe
• Largely historical debate
• More productive???
• Why evolve flight?
• To help escape from predators
• To help catch flying or speedy prey
• To help move from place to place (leaping or
  gliding)
• Vigilence
• Migration, etc
• Nomadism
• To free the hindlegs for use as weapons

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Adaptive Radiations (within adaptive radiations)

• Evolution of ecological diversity within a
  rapidly multiplying lineage (Schluter, 2000)
• 150-160 MYA
• gt10,000 species extant
• Fraction of what has existed

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• Ancestor Bird

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Bird Classification
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Old Classification

• Old Fashion
• - based on colour
• - based on type flying birds/non flying birds
• - based on food type insectivorous/piscivorous/g
  rainivorous/frugivorous

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Systematics

• Imprint of Linneaus 1758
• Binomial nomenclature
• Upupa epops
• Standard English Names (Common Name)
• In India there is no common naming system for the
  classification

Kingdom Phylum Class Order From Genus species
species
Genus
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Current Classification

• 29 orders
• 187 Families
• 2000 Genera
• 10000 species
• Rapidly changing

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Current Classification
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Molecular Phylogeny

• Started in 1990 by Sibley and Ahlquist
• DNA-DNA Hybridization
• In 2003 Dr. Paul Herbert used mt DNA to Barcode
  the bird species.
• He identified 4 new species of North American
  birds
• This is revolution in the Avian Taxonomy

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Many Things to come in Future

• In India there are only once study on mtDNA i.e.
  Large-billed Reed Warbler Acrocephalus orinus

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Thank You