Introduction into tetrapod evolution

Question 1

what is tetrapod greek for

Answer 1

four foot
= they are the vertebrates which left the water and colonized the land

Question 2

what are tetrapod’s in terms of their phylogeny

Answer 2

a superclass within
1) Kingdom = Animalia
2) subkingdom= Eumetazoa
3) clade= Bilateria (bilateral symmetry)
4) superphylum= Deuterostomia (anus develops before mouth)
5) phylum= Chordata

Question 3

what are the defining features of chordates (including tunicates and cephalochordates)

Answer 3

1) pharyngeal slit = series of opening which connect the inside of the throat to the outside of the neck

2)Dorsal nerve cord = bundle of nerve fibres connecting the brain with muscles and organs

3) notochord= cartilaginous rods running underneath and supporting the nerve chord

4) post- anal tail = extension of the body past the anal opening

Question 4

what are the defining features of vertebrates

Answer 4

1) vertebral column = replaces the original notochord after embryonic development

2) centrum= the main bony disk-shaped portion of the vertebra which forms around/replaces the notochord

3) Neural arch= on the dorsal side of the centrum which the nerve cord passes through

4) increased size and activity associated with predation due to bigger brain/more complex sensory systems

Question 5

outline how the notochord allows locomotion/propulsion

Answer 5

large chordates use serial contraction of segmented muscle bands in the trunk of the tail

1) notochord and centrum stiffens the body so it bends from side to side as muscles contract = propulsion

= no notochord = muscle contarct would cause body shortening not propulsion

Question 6

what did tetrapod’s evolve from

Answer 6

Sarcopterygii= lobe finned fish in the middle of the devonion period

Question 7

outline when tetra pods began to become terrestrial and what terrestrial life requires

Answer 7

380 MYA first appeared on land
needed
1) efficient systems for o2 extraction/transport = spiracles on top of head, possessed lungs but used gills as primary means

2) ways of eliminating waste but retaining water

3) maintenance of stable body temp = low surface area to volume ration to minmise rate of heat gain/loss

Question 8

how can arriving on land be an adaptive advantage for early tetrapods

Answer 8

air temps can be much higher than water so more direct thermal regulation thus basking can heat ip and allow to operate at higher metabolic rate

Question 9

what do higher levels of activity require

Answer 9

1) specialised gas exchange structures above and more than cutaneous respiration

2) effective cardiovascular system

3) ability to acquire and process sensory info rapidly

Question 10

give some examples of anaminotes and amniotes

Answer 10

An = fish and amphibians
A= mammals, birds and reptiles

Question 11

what are the three layers produced by the feotus which distinguish amniotes and anaminotes

Answer 11

1) amnion= surrounds the embryo providing a stable enviro protecting from mechanical shock

2) allantois = allows gass diffusion and stores nitrogenous waste

3) chorion= outer membrane also involved in gas exchange

Question 12

outline the evolution of the amniotic egg and what their presence allowed

Answer 12

310 MYA first amniotes appeared allowing survival out of water, process waste and more efficient respiratory exchange menaing they can grow larger

Question 13

what are the two major lineages within the amnoites

Answer 13

1) saurosids = reptiles, birds, crocodiles and turtles

2)synapsids = mammals

Question 14

outline the differences in skull structure between the synapsids and saurosids

Answer 14

sy = one opening behind the eye

Sa = 1) anapsids (turtles) - no opening behind the eye 2) diapsids (reptiles/birds)= two openings behind the eye

Question 15

380 million years ago was known as the devonion period what is another name for this

Answer 15

The age of fishes= due to 200 million years earlier of evolution, the verterbrates produces an explosion of fish-like animals,

Question 16

what two groups are the early terrestrial pioneers divided into

Answer 16

1) modern amphibians e.g. frogs, salamanders and caecilians

2) modern amniotes e.g. mammals, turtles, crocodiles and birds, lizards and snakes

Question 17

what is meant by the geological column

Answer 17

the name scientists give to the succession of times, dates and names into which earths history is divided into; depicted either as a vertical column of a clock face

Question 18

what is meant by the term Phanerozoic

Answer 18

the interval for which there are abundant fossils in the rocks meaning visable life= represents a time of about 600 million years

Question 19

what are the three eras that the Phanerozoic is divided into

Answer 19

named according to what proportion of biota is resembled
1) Paleozoic = ancient life
2) Mesozoic = middle life
3) Cenozoic = recent life

these are further divided into periods and periods into stages

Question 20

Types of fossils can be categorized according to what is preserved or how it is preserved- what are the different type of fossil names

Answer 20

1) body fossils = show the anatomy of the spp preserved allowing evolutionary relationships and functional morphology to be explored
2) trace fossils= preserved impressions of features than an animal has made e.g. footprints or burrows

Question 21

why are fossils from earlier in earths history less well preserved

Answer 21

dissolution by acids can remove calcium and allow bones to bend into unnatural shapes

rock movements, faulting of heat from igneous activity can distort or fracture them

Question 22

other than fossilisation what are some other ways of preserving old spp

Answer 22

1) Amber= resin produced by certain trees can trap insects or small verterbrates- trees didnt evolove in paleozoic

2) mummification= spp die in arid conditions their bodies become air dried, buried in sand and when sand hardens –>sandstone= tissue preserved as well as bones

Question 23

what is phylogeny

Answer 23

the name given to the evolutionary relationships and history of the animal in question, and the practise of working out its phylogenetics