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reptiles are closer to birds or amphibians?
birds
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what kind of skull does turtles have?
anapsid (no hole, just orbit)
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birds and crocodiles
- have diapsid skull, which has two pairs of temporal openings with orbit
- also tuataras and squamata has it too
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synpside
mammals which one pair of lateral temporal opening
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what are dinosaurs closest to?
birds and crocodiles
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what groups are snakes, worm lizards and lizards in?
squamata: males with hemipenes (external reproductive organs), characteristics of skeleton
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lepidosaurians
- tuataras (special type of reptiles) and squamata group
- skin shed in one piece, characteristics of bone growth, skull, pelvis feet
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amniotes
extraembryonic membranes of amnion, chorion and allantois
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reptiles are more closely related to what than what?
more close to birds and mammals than to amphibians
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why are reptiles and amphibians grouped together
- because they are cold blooded (ectotherms, cannot produce their own heat)
- whereas birds and mammals can produce their own heat.
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classes of reptiles
- testudines order (turtles)
- crocodilia
- squamata
- sphenodonta (tuatara)
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general reproductive characteristics of reptiles
- amniotic eggs with shell
- internal fertilization
- oviparous, ovoviviparous and viviparous (few)
- direct development
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oviparous
produce eggs that hatch outside the body
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ovoviviparous
- there's no placental connection and the unborn young is nourished by egg yolk
- eggs hatched within the body, young are born alive
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viviparous
- all mammals except the monotremes
- eggs hatched inside with placenta
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general characteristics of reptiles
- epidermal scales and claws
- 5 digits on each limb
- thoracic ribs (except turtles), important for respiration, neg pressure expand
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eggs of reptiles
- amnion: inner membrane surrounding the baby
- leathery shell
- yolk
- chorion: outmost membrane around embryo that protects the baby, allow transfer of nutrients from maternal blood to fetal blood
- Allantois: sac like structure allows for gas exchange, highly vascularized and allow waste to exchange
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melanophores
- cells in skin that can change colors by dispersing or congregating
- reptile skin is always covered in scales to keep moisture (not dependent on water anymore)
- amphibians still depend on water
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osteoderm
bony deposits forming scales in dermis layer
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flexible hinge
part the curves in in scale
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lonesome george
- lives in Galapagos island
- giant turtle, lonely survivor
- necks and shell shaped to best suit the amount of food and the type of food
- (domed shaped shell and short necks when there's a lot of food)
- saddlelike shell (like George) help reach more food (longer necks)
- can live for a year without food or water
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turtle sex determination
- depends on temperature (males develop at lower temp (below 20C)
- crocodiles, males develop at higher temp
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squamata
- shed their epidermal scales with growth
- geckos with fat tails
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chameleon (what order?)
- squamata
- change color based on mood and temp
- chromatophore (less dense and more concentrated changes color)
- remarkable vision (pupil moving)
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viperidae
- vipers are family of snake
- sheathed fangs at the front of mouth that allow deep penetration to release venom
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elapidae
short, immovable fangs at front of mouth
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colubridae
- rear fanged (or no fangs)
- mostly nonpoisonous
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hydrophiidae
- sea snakes
- extremely poisonous
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boidae
- constrictors, used to kill prey
- many retain vestigial pelvic structures
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parts of viperidae
- pit organ to sense heat (they mostly eat at night), has receptor nerve endings packed with mitochondria
- discharge orifice to discharge venom
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komodo dragon
- largest living lizard in the world
- kills with virulent bacteria on teeth (blood poisoning)
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ectotherm vs. endotherm
- ectotherm: need external energy to increase temp (bask in sun), snake
- endotherms: (keep constant temp), need regular amount of food to regulate physiological processes, bobcat
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heat sources that lose energy
- conduction: lose heat by touching other materials
- evaporation loses heat too
- thermal radiation back to sun
- convection (hot air rises, cool air falls)
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characteristics of birds
- bipedal
- feathers for insulation and lift and thrust
- toothless beaks
- wings with fused digits
- ability to fly
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what are adaptations associated with flight
- skeleton
- musculature
- physiology
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earliest bird, rarest bird
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why do birds have so much adaptive radiation?
- they can fly and move around/ complicated behaviors
- diff mating calls, small mistake creates hybrids
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bowerbirds
make nest look pretty to attract females
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hawaiian honeycreepers
- radiation within smaller groups
- radiation in body parts
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current classification of birds
- 29 orders
- 187 families
- 2000+genera
- 10,000 species
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regional community vs local community
- regional is the landscape
- local is the habitat within that landscape
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what is used to construct phylogenic tree of birds
- based on shared, derived characteristics (like the pattern on their back)
- diff birds share same middle ear bone
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archaeopteryx
- teeth, 3 digits on fingers, big tail
- in Germany
- undeveloped sternum (breastbone compared to modern birds)
- wings not as strong, longer tail
- transition form between reptiles and birds (support Darwinism evolution)
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cursorial and arboreal hypothesis
- cursorial (ground up)
- arboreal (trees down)
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herman von meyer
archaeopteryx lithographica
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ground up hypothesis
- assume biped, cursorial (having limbs adapted for running) ancestor
- bones of legs are long
- large legs for running muscle attachment
- once running, use feathers for other things like catching insects, and picking up minimum speed for lift.
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trees down hypothesis
- semi bipedal leaping and gliding ancestor
- claws to scale trees, retained in winged appendages
- short hand wing (power), long arm wing (lift)
- no keeled sternum
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what kind of fish gives rise to amphibians
lungfish
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why evolve flight?
- escape predators
- help catch flying or speedy prey
- help move from place to place (leaping or gliding), vigilance, migration, nomadism
- free hind legs for use as weapon
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thecodonts and therapsids
- therapsids (mammals)
- thecodonts (dinosaurs, birds, crocodiles)
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all modern birds lie within neornithes, what are the two subdivisions
flightless or little flying and all others
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archosauria
birds and crocodiles
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function of feathers
- flight
- heat conservation (reduced convective and evaporative heat loss, increased insulation)
- made of keratin
- most conspicuous integumental derivative
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feather development
- interaction between epidermis and dermal mesenchyme
- form dermal papila (bump in dermis, also called placode)
- mitotic divisions in a collar zone of stratum germinativum to form crown of barbs
- covered by a horny sheath of epidermis
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differential cell division on one side of the papilla
- timing of expression of two proteins (Shh and Bmp2)
- forms shaft, carrying barbs
- base of the feather recedes into the skin
- degeneration of epidermal sheath
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types of feather
- contour
- semiplumes
- down
- bristles
- filoplume
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contour
- insulating and flight
- vanes symmetrical and vanes asymmetrical
- wings, and tails
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semiplumes
- rachis greater than barbs
- ostrich
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down
- rachis less than barbs
- insulating
- adult and natal (lost)
- powder down for waterproofing
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bristles
- little or no vane, little barbs
- on face on whip-poor-will
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filoplume
- pennaceous feathers (quill)
- attached to sensory corpuscles in skin
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how do birds sing?
no vocal cords, fill cavity with air and vibrate cavity
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Pigment colorization in birds comes from three different groups
- carotenoids (from plants, bright colors)
- melanins (brown and black)
- porphyrines (modifying amino acids, produce a range of colors)
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