BIO 1130 Lecture Notes - Lecture 37: Oviparity, Adaptive Radiation, Autapomorphy
24 Jan 2017
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Phanerozoic - Cenozoic era
ā Continents shift into final locations
ā Therapsids have survived
ā Survivor: reptile with feathers - unique: feathers were used to thermoregulate
ā Endothermy: by birds and mammals - generate heat to maintain body temp (homeothermy -
keeping body at precise and constant temp)
ā Amniote animals: includes reptiles, birds & mammals - have eggs with amnion (water-filled sac)
surrounding the developing embryo
ā Birds: same as therapsids - feeding when cool
ā Feathers: not only found in birds (were common in dinosaurs)
ā Used feathers for catch prey (insects) - by swiping through air
ā Ground-up theory of birds: while birds were trying to catch prey, realized that swiping up
and down could lift them & help escape from predator (origins of flight)
ā Tree-down theory: bird climbs tree, jumps down from branch and glides with feathers as it
eats insects
ā Feather becomes complex - keratinized structure (beta keratin because reptile)
ā Small elements that are locked together ā makes lightweight structure w/ holes
that are small enough that can push against air
ā Barb: branches of a feather, possess barbules; maintain feathersā structures
(even during vigorous activity)
ā Barbule: hook-like processes on barbs of feathers - interlock filaments of feather
together; maintain feathersā structures (even during vigorous activity)
ā Lighter organism ā altered bones to become light ā tail gone, jaw gone (replaced by
beak of keratin), vertebrate gone, and # of bones in wing reduced
ā Wing: only skinny piece of bone (even though it looks big) ā feathers do all the
work
ā Power to lift wing becomes centralized ā all organ systems centralized (center of
gravity) ā lifting force is above center of gravity
ā Muscle lifts wing ā 1 pulls up, another 1 pulls down
ā Sternal keel: modified sternum (breastbone) in birds; the attachment
(anchor) of the flight muscles
ā Bones are filled with air (not solid) = lighter (pneumatized bone)
ā Engage in parental care: does make appearance with reptiles ā but birds lay eggs,
incubate & take care of offspring
ā Few offspring every year, but guaranteed success of offspring ā good, effective
reproductive strategy
ā Mammals - great apes: includes chimpanzees, gorillas & orangutans; group that humans have
the most chromosomal similarities to
ā Synapsid: mammals and mammal-like reptiles (ex. humans)
ā Synapsid skull - 1 opening for jaw muscle
ā Keratin - alpha keratin only (in skin) (automorphy of mammals) ā makes hair, toenails
ā Skin: glandular ā loaded with glands = makes materials on surface of skin
ā Later modified to make nourishment for feeding young with ā mammary gland
& lactation
ā Follicle cell: makes hair
ā Sebaceous gland: makes oils and waxes (need to keep hair supple and smooth)
ā need to be able to lift hair up (and with hairs going down) = makes insulative
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Document Summary
Survivor: reptile with feathers - unique: feathers were used to thermoregulate. Endothermy: by birds and mammals - generate heat to maintain body temp (homeothermy - keeping body at precise and constant temp) Amniote animals: includes reptiles, birds & mammals - have eggs with amnion (water-filled sac) surrounding the developing embryo. Birds: same as therapsids - feeding when cool. Feathers: not only found in birds (were common in dinosaurs) Used feathers for catch prey (insects) - by swiping through air. Ground-up theory of birds: while birds were trying to catch prey, realized that swiping up and down could lift them & help escape from predator (origins of flight) Tree-down theory: bird climbs tree, jumps down from branch and glides with feathers as it eats insects. Feather becomes complex - keratinized structure (beta keratin because reptile) Small elements that are locked together makes lightweight structure w/ holes that are small enough that can push against air.
