week 8

Question 1

who first conceived the theory of evolution

Answer 1

darwin

Question 2

define adaptation

Answer 2

an evolved trait that serves a certain function

Question 3

define heritable trait

Answer 3

a characteristic within an organism’s genetic code that can be passed down to offspring

Question 4

define evolution

Answer 4

theory that states the success of different heritable adaptations causes certain traits to be increasingly concentrated in a population, eventually changing the population over time

Question 5

define natural selection

Answer 5

competitive selective process by which detrimental traits are lost and advantageous traits are kept within a population

Question 6

Dinosauria. what is it

Answer 6

a group formed by ornithischians, saurischians, their most recent common ancestor, and all of its descendants

Question 7

what are ornthischia

Answer 7

‘bird hipped’ group composed of hadrosaurs, ceratopsians, pachycephalosaurs, stegosaurs, and ankylosaurs, their most recent common ancestor, and all their descendants

Question 8

what are saurischia

Answer 8

‘lizard hipped’ group formed by theropods, sauropods, and prosauropods, their most recent CA, and all their descendants

Question 9

what is a character

Answer 9

any heritable trait that can be described and labelled. used mostly in taxonomy

Question 10

what is a synapomorphy?

Answer 10

a character that stems from a common ancestor and is passed down to its descendants

Question 11

what is convergent evolution

Answer 11

the independent evolution of similar structures by different lineages, due to organisms facing similar ecological or environ pressures

Question 12

what are the four principles of natsel?

Answer 12

1. a trait is heritable
2. mutations can occur
3. an organism’s trait impacts its survival, such that advantageous traits benefit it and disadvantageous traits harm it
4. natural environ forces evolution virtue of having limited resources

Question 13

is evolution random or directional?

Answer 13

directional - the processes behind evo are random, but evo itself is directional in that traits are selected for and against

Question 14

what is a shared derived trait of ornithischia?

Answer 14

special bone in lower jaw that forms a beak (the predentary)

this character is unique to ornithischia

Question 15

spinosaurus and ouranosaurus both have a big spine. are they related?

Answer 15

really really distantly. spinosaurus are theropod saurischians and ouranosaurus are hadrosaur ornithischians. would require one species completely rewriting its pubis, losing/developing predentary, etc

–> parsimony suggests its convergent evo

Question 16

bats, birds, and pterosaurs all have wings. are they related?

Answer 16

no - they developed wings differently
bats: wing made of membrane stretching between five fingers
birds: wing made of feathers, w ‘hand’ bones fused into one bone
pterosaurs: wing made of membrane stretched from one elongated finger

Question 17

phylogenetic trees contain nodes, branches, and clades. define

Answer 17

node: point at which two species diverge; indicates CA for the clade

branch: an independent lineage coming off a node

clade: a group of species that share a common ancestor, and implicitly some synapomorphies from said CA

Question 18

who was the first dude to link birds to dinos? what evidence did he have? what is one problem he ran into?

Answer 18

huxley thought Arhceopteryx was the missing link, w long wing-like feathers and tail feathers similar to a birds, but w teeth, claws, and tail vertebrae of dinos

problem: birds have clavicles and dinos don’t. except on further analysis we realized they do, especially the theropods

Question 19

what is a bird?

Answer 19

some say clade Avea, which is a clade of birds; some say clade Avialea, which is flying dinosaurs; some say any feathered dinosaur.

however there are problems w each (essentially, at what point do dinos become more birdlike than dino-like?)

tentatively we say crown birds, which distinguishes dinosaurs and birds by defining a bird as the last CA of all living birds. this includes some extinct species such as dodo birds, but excludes dinosaurs as well as some birds that were around at the time of dinos.
under this definition, Archaeopteryx is not a bird, but a dino

Question 20

what is a hadrosaur example of synapomorphy?

Answer 20

lambeosaurus, corythosaurus, parasaurolophus all have crests but they appear to be different. however, that they have such crests is a synamopomorphy

Question 21

what is the relevance of the ceratopsian syncervical?

Answer 21

an indicator of later ceratopsians that is not found in earlier ceratopsians

Question 22

huxley thought birds came from dinos, but he has a problem. what was it

Answer 22

we’ve never found dino clavicles, but birds have them

except they actually did in the meat eating dinos, scientists just never noticed them