Unit 2 Notes
6: Birds
• Vertebrate diversity
o 50,000 species
§ 25,000 fish
§ 5,000 amphibians
§ 7,000 reptiles
§ 10,000 birds
§ 5,000 mammals
o Evolution
§ Cambrian period, phylum Chordata
• Subphylums Vertebrata, Cephalochordata (lancelets),
Urochordata (tunicates)
o Tunicates are filter-feeders
• Notochord: hollow dorsal nerve cord
• Pharyngeal gill slits
• Post-anal tail
§ Ordovician period
• Evolution of jaws
• No longer limited to filter feeding or eating only soft, dead things
• Creation of predation
§ Silurian period
• Began to develop bones and swim bladder
o Swim bladder allows neutral buoyancy
o Do not need to keep swimming to stay in a certain place
§ Devonian period
• Age of fishes
§ Carboniferous period
• Evolution of feet
• Evolution of amniotic egg
o Hard shell to lay eggs on land
o Leathery outermost membrane in early amniotic egg
§ Permian period
• Age of plants
§ Triassic period
• Evolution of milk production and hair
• Mammals
§ Jurassic period
• Evolution of feathers
• Birds and dinosaurs
, § Cretaceous period
§ Tertiary period
• Bird Evolution
o Birds radiated in Mesozoic, alongside Pterosaurs
§ Competition between birds and pterosaurs may have selected for
increased pterosaur size
• To reduce competition
• Increase in size only after birds evolved
o
o Archosaurs
§ Feathers
• Probably evolved for ornamentation, then endothermy, then
flight
o Endothermy: insulation
• Flight evolved in several lineages
o Flight basics
§ Faster speed of wind over wing = more lift
§ Greater angle of attack = more lift = more drag
§ Mass increases with cubic volume
• Need balance between wing size and wing
loading
§ Larger, heavy birds need proportionally larger
wings to compensate
• To maintain same wing loading
• Or need faster flight to generate more lift to
offset greater loading
§ High aspect ratio means low drag
• Aspect ratio is length:width ratio
• Long and skinny wing
, • Like albatross, which can go 10,000 miles
without a wing flap
§ Low aspect ratio means maneuverable, but stall
risk at slow speeds due to drag
• Like owl
§ Peregrine falcon is fastest animal
• Dives at 230mph
o V Formation
§ Vortices off leading bird create updraft to lift the
bird behind
§ Negates some of the bird’s own downdraft and
turbulence
• Theropods
o 3 toes
o Hollow bones
o Feathered T. rex
§ Smaller tyrannids had feathers
• Like Yutyrranus, lived before T. Rex
§ Juvenile T. rex had feathers
§ Lost feathers to assist with heat disappation
o Anchiornis huxleyi (feathered) evolved 160mya
o Archaeopteryx lithographica evolved 150mya
o Beipiaosaurus (feathered) evolved 125mya
o Sinosauropteryx (feathered) evolved 123mya
o Raptors (Dromaeosauridae)
§ Feathered
§ 166-66mya
§ Microraptor gui glided and had asymmetrical flight
feathers
• 120mya
• Maniraptoria
o Long forelimbs
o 3 toes
o Tianyulong, an Ortnithiscian, evolved 160mya
7: Birds 2
• Phylogeny
o Some modern lineages of birds diverged in Mesozoic
o Major radiations in most bird lineages in the absence of dinosaurs and
pterosaurs
§ After 65mya (K-T boundary)
§ Phorusracidae, terror birds
, • Filled niche of top terrestrial predators in South America from 63-
1.8mya
• Ranged into Florida and Texas
• Not related to struthioformes, but to falcons and South American
seriemas
§ Paleognathae, primitive palate
• Jaw is primitive and reptilian
• Omnivorous
• Has penis
o Most male birds do not have penises
o Galloanserae: penis present
o Neoavis: no penis
• Includes elephant bird
o Heaviest ever
o 10 feet tall, 800lbs.
o Madagascar
o Driven to extinction in 1600s
• Ecology of the Ratites
o Ostriches, emus, rheas, tinamous
§ Omnivores
o Cassowary
§ Frugivore
§ Keystone species for Australian rain forests by
dispersing seeds of hundreds of rainforest plants
o Kiwi
§ Dwarfism on islands
§ Largest egg relative to body size of any bird
§ Eats mostly worms, millipedes, and other
terrestrial invertebrates
o Moas
§ New Zealand
§ 9 species
§ Herbivores
• Rocks in gizzard for grinding plant material
§ Up to 12ft tall
§ Extinct by 1445
• Polynesians colonized around 1300
§ Argentine Lake Duck
• When not corkscrewing out of the duck, penis fully retracts into
abdomen
o Galloanserae
• Female ducks have corkscrew shaped oviduct
6: Birds
• Vertebrate diversity
o 50,000 species
§ 25,000 fish
§ 5,000 amphibians
§ 7,000 reptiles
§ 10,000 birds
§ 5,000 mammals
o Evolution
§ Cambrian period, phylum Chordata
• Subphylums Vertebrata, Cephalochordata (lancelets),
Urochordata (tunicates)
o Tunicates are filter-feeders
• Notochord: hollow dorsal nerve cord
• Pharyngeal gill slits
• Post-anal tail
§ Ordovician period
• Evolution of jaws
• No longer limited to filter feeding or eating only soft, dead things
• Creation of predation
§ Silurian period
• Began to develop bones and swim bladder
o Swim bladder allows neutral buoyancy
o Do not need to keep swimming to stay in a certain place
§ Devonian period
• Age of fishes
§ Carboniferous period
• Evolution of feet
• Evolution of amniotic egg
o Hard shell to lay eggs on land
o Leathery outermost membrane in early amniotic egg
§ Permian period
• Age of plants
§ Triassic period
• Evolution of milk production and hair
• Mammals
§ Jurassic period
• Evolution of feathers
• Birds and dinosaurs
, § Cretaceous period
§ Tertiary period
• Bird Evolution
o Birds radiated in Mesozoic, alongside Pterosaurs
§ Competition between birds and pterosaurs may have selected for
increased pterosaur size
• To reduce competition
• Increase in size only after birds evolved
o
o Archosaurs
§ Feathers
• Probably evolved for ornamentation, then endothermy, then
flight
o Endothermy: insulation
• Flight evolved in several lineages
o Flight basics
§ Faster speed of wind over wing = more lift
§ Greater angle of attack = more lift = more drag
§ Mass increases with cubic volume
• Need balance between wing size and wing
loading
§ Larger, heavy birds need proportionally larger
wings to compensate
• To maintain same wing loading
• Or need faster flight to generate more lift to
offset greater loading
§ High aspect ratio means low drag
• Aspect ratio is length:width ratio
• Long and skinny wing
, • Like albatross, which can go 10,000 miles
without a wing flap
§ Low aspect ratio means maneuverable, but stall
risk at slow speeds due to drag
• Like owl
§ Peregrine falcon is fastest animal
• Dives at 230mph
o V Formation
§ Vortices off leading bird create updraft to lift the
bird behind
§ Negates some of the bird’s own downdraft and
turbulence
• Theropods
o 3 toes
o Hollow bones
o Feathered T. rex
§ Smaller tyrannids had feathers
• Like Yutyrranus, lived before T. Rex
§ Juvenile T. rex had feathers
§ Lost feathers to assist with heat disappation
o Anchiornis huxleyi (feathered) evolved 160mya
o Archaeopteryx lithographica evolved 150mya
o Beipiaosaurus (feathered) evolved 125mya
o Sinosauropteryx (feathered) evolved 123mya
o Raptors (Dromaeosauridae)
§ Feathered
§ 166-66mya
§ Microraptor gui glided and had asymmetrical flight
feathers
• 120mya
• Maniraptoria
o Long forelimbs
o 3 toes
o Tianyulong, an Ortnithiscian, evolved 160mya
7: Birds 2
• Phylogeny
o Some modern lineages of birds diverged in Mesozoic
o Major radiations in most bird lineages in the absence of dinosaurs and
pterosaurs
§ After 65mya (K-T boundary)
§ Phorusracidae, terror birds
, • Filled niche of top terrestrial predators in South America from 63-
1.8mya
• Ranged into Florida and Texas
• Not related to struthioformes, but to falcons and South American
seriemas
§ Paleognathae, primitive palate
• Jaw is primitive and reptilian
• Omnivorous
• Has penis
o Most male birds do not have penises
o Galloanserae: penis present
o Neoavis: no penis
• Includes elephant bird
o Heaviest ever
o 10 feet tall, 800lbs.
o Madagascar
o Driven to extinction in 1600s
• Ecology of the Ratites
o Ostriches, emus, rheas, tinamous
§ Omnivores
o Cassowary
§ Frugivore
§ Keystone species for Australian rain forests by
dispersing seeds of hundreds of rainforest plants
o Kiwi
§ Dwarfism on islands
§ Largest egg relative to body size of any bird
§ Eats mostly worms, millipedes, and other
terrestrial invertebrates
o Moas
§ New Zealand
§ 9 species
§ Herbivores
• Rocks in gizzard for grinding plant material
§ Up to 12ft tall
§ Extinct by 1445
• Polynesians colonized around 1300
§ Argentine Lake Duck
• When not corkscrewing out of the duck, penis fully retracts into
abdomen
o Galloanserae
• Female ducks have corkscrew shaped oviduct
