Lecture 22: Reptiles & Birds

Question 1

how did reptiles perfect the transition to terrestrial life?

Answer 1

• new leg arrangements
• more efficient lungs and heart
• watertight coverings for skin and eggs

Question 2

what are defining traits of reptiles?

Answer 2

• amniotic eggs
• dry skin
• thoracic breathing
• improved kidneys

Question 3

who are the amniotes?

Answer 3

-all that have amniotic eggs (bird, reptiles, mammals)

Question 4

what are the benefits of amniotic eggs?

Answer 4

• they’re independent and eliminate the need for water since they contain a food source
• have a watertight shell
• have 4 inter-membranes

Question 5

internal fertilization

Answer 5

• amniotic eggs make external fertilization impossible
• sperm has to hit egg before the membrane forms
• some reptiles and birds have external gestation though

Question 6

reptile skin

Answer 6

• not moist, made of keratin rich scales (not homologous)

- since not moist, they’re entirely dependent on their lungs and therefore have an increased lung capacity

Question 7

thoracic breathing

Answer 7

-only limited to size of lungs so greatly increases gas intake

Question 8

glottal breathing

Answer 8

-limits breath to size of mouth (how amphibians breathe)

Question 9

ectothermy

Answer 9

• body temp changes with temp of environment

- i.e. can move in and out of sunlight to control body temp

Question 10

endothermy

Answer 10

-maintain their temp using internal body functions (need to maintain this temp in order to survive)

Question 11

benefits of reptile jaws

Answer 11

• very strong, more efficient

- categorized by the number of openings in the skull behind eyes

Question 12

synapsids

Answer 12

• one opening in skull behind eye

- earliest reptiles

Question 13

therapsids

Answer 13

• evolved from synapsids
• endothermic w/ a little bit of fur
• most of them died out when the dinosaurs came, except for mammals

Question 14

diapsids

Answer 14

• 2 openings in skull behind eyes, led to birds

- contains all extant reptiles and extinct dinosaurs

Question 15

archosaurs

Answer 15

• monophyletic group in diapsids
• 1st to walk on 2 legs
• had row of bony plates like modern crocodiles

Question 16

lepidosaurs

Answer 16

-diapsids that aren’t archosaurs

Question 17

tuataras

Answer 17

• lepidosaurs
• only 2 remaining species
• only found on a small group of islands

Question 18

lizards and snakes

Answer 18

• squamates & lepidosaurs
• almost all carnivorous
• some have 2 peni
• most lizards walk on 4 legs
• snakes are limbless and can unhinge their jaws and some produce venom

Question 19

turtles and tortoises

Answer 19

• neither individually are monophyletic, but together they are
• have no teeth and have protective shell which they are attached to
• marine ones have to return to land to lay eggs

Question 20

crocodilians

Answer 20

• out-group to extinct dinosaurs
• large stealthy predators, mostly aquatic
• eyes and nostril on top of snouts
• enormous mother with strong neck muscles
• types: crocodiles, alligators, caimans, gavials

Question 21

crocodilian parental care

Answer 21

• spend a lot of time with their young
• both parents will carry babies carefully in mouths
• moms even to teach them to hunt

Question 22

who did birds evolve from?

Answer 22

archosaurs

Question 23

theropods

Answer 23

• evolved feathers, gave rise to birds
• group of predatory dinosaurs
• all had bipedal stance, hollow bones, swiveling wrists, 3 fingered hands and feet, and backwards pelvises
• types: velociraptor

Question 24

4 traits that birds share

Answer 24

• feathers
• flight skeletons
• improved lung design
• endothermy

Question 25

facts about feathers

Answer 25

- they give lift for flight and provide heat - they're very flexible but strong bc secondary branches hook together with barbs - large ones also have thin quills - fan-like tail feathers stabilize the bird and down feathers keep it insulated

Question 26

bird skeletons

Answer 26

- bones are thin and hollow to help with flying, many are also fused together - gives it a rigid skeleton which gives it a sturdy frame to support flying muscles - muscles connect to keel for powerful flight

Question 27

bird lungs

Answer 27

- flight takes a lot of oxygen and energy | - bird lungs take in oxygen better than in any other organism

Question 28

endothermy in birds

Answer 28

- body temp must be higher than in most mammals b/c it gives them good metabolism and ATP production - all the energy used for flight leads to heat loss (that's why their feathers are so insulating)

Question 29

beak and foot morphology

Answer 29

- can tell a lot about a bird from its beak/feet | - types: you can tell a duck is aquatic from its webbed feet and filtering beak

Question 30

general order of bird evolution

Answer 30

large flightless birds (ostriches) whose ancestors had flight (therefore flight was lost), after that you have water fowl, then owls/Swiffers/Woodpeckers, then Passeriformes.

Question 31

passeriformes

Answer 31

- song birds - most successful group of bird - 1/2 of all birds are them

Question 32

pelycosaurs

Answer 32

- gradually replaced amphibians - had long, sharp teeth and could kill animals of their own size - some of 1st synapsids