lecture 12

Question 1

When multicellular organisms originate from (Historically)

Answer 1

End of precambrian, start of Paleozoic

Question 2

The earliest known occurrence of multiceullar animals are the _________
Some of them resemble ________

Answer 2

• Ediacaran fauna

- modern jelllyfish and segmented worms

Question 3

study of early diversity of life dependent on

DNA evidence can offer _______

Answer 3

fossil evidence

hints with respect to timeline

Question 4

Sedimentary rock

Answer 4

• preserves fossils

- pile up over geologic time and become rock

Question 5

Factors that create a high chance of preservation

Answer 5

• being buried quickly

- having hard parts

Question 6

Law of superposition aids in _______

Answer 6

determining the relative age of fossils

Question 7

Modernly, fossils can be dated with ______

Answer 7

elemental isotopes, in accompanying rock

Question 8

Half-life

Answer 8

Length of time required for exactly one half of original isotope to decay

Question 9

Half-life determination technique

Answer 9

Measure amount of original(mother) isotope as well as amount of decay(daughter) isotope

Question 10

The radioisotope is the ___________

The decay product is the ________

Answer 10

parent isotope

daughter isotope

Question 11

Beginning of Cambrian period introduced

Answer 11

a major increase in the diversity of animal species

• including all invertebrates we see today
• 100 animal groups(30 still today)

Question 12

The Burgess shale is

Answer 12

a highly unusual preservation of soft bodied organisms

Question 13

Biota of burgess shale

Answer 13

typical of cambrian deposits

Question 14

Hard-part bearing organisms of burgess shale

Answer 14

make up as little as 14% of the community

Question 15

Burgess shale biota has a range of
60% _____
30% __________
10% _______

Answer 15

free swimming organisms & common bottom dwelling organisms
60% feed on organic content on sea floor
30% filter particles from the water
10% predators or scavengers

Question 16

Two hypothesis for cause of Cambrian Explosion

Answer 16

1. Advances just before the explosion allowed subsequent groups to exploit new environments and rapidly adapt to them
2. Diversity may be related to rising oxygen levels(They had high oxygen levels then)

Question 17

Mid-Ordovician characteristics

Answer 17

• warm and humid
• marine invertebrates very diverse
• ancestral jawless fish present
• invasion of land by plants and arthropods (set of new environments)

Question 18

Land plant evolution fun facts (4)

Answer 18

• evolved 472 million years ago
• lack stems or roots
• very important evolutionary breakthrough
• shared a common ancestor with the modern order of Coleochaetales(algae)( also bryophytes)
  
  • evidence for the relationship found in morphology and genetics

Question 19

Bryophytes

Answer 19

all land plants with no true vascular tissue (non-vascular plants)

Question 20

Pneumodesmus newmani

Answer 20

• oldest hard body creature to live on land
• 428 million years ago
• late silurian

Question 21

Challenges to living on land

Answer 21

1. Gravity requires some rigidity
2. Water is no longer everywhere
3. Obtaining sufficient energy
4. Temp on land is highly variable compared to water

Question 22

Adaptations to gravity on land

Answer 22

Animals - muscles and skeletons to move on land

Animals - roots for anchoring, rigid cells to maintain vertical stance

Question 23

Adaptations to water not being everywhere on land

Answer 23

Animals - Outer layer that prevents inner tissues from drying out
Plants - Waxy cuticle to retain water, use roots to obtain ground water

Question 24

Adaptations to obtaining sufficient energy

Answer 24

Animals - are heterotrophs and develop new means of eating plants and other animals
Plants - grow upright to obtain sufficient sunlight for photosynthesis, requires support tissue

Question 25

Adaptations to temp on land being highly variable

Answer 25

Animals - burrow or rest in shade, become nocturnal, sweat glands, fur feathers, migration, hybernation
Plants - evaporative cooling through pores, develop spores that can persist through cold/dry periods,

Question 26

Consequence of a vertebrate centric point of view

Answer 26

• much of the earths history has been assigned names based on newly derived vertebrates, the vertebrate did not dominate the dominate the landscape but instead say a rise in its own diversity

Question 27

Once life on land had taken hold

Answer 27

• the majority of new niches had been created

- with no new niches there were no drastic changes in morphology or body plans

Question 28

Life has increased and decreased in diversity

Answer 28

• a steady rate of extinction and five major extinction events (life finding new ways to solve the same problem)

Question 29

percentage of animal species that are inverts

Answer 29

99%

side note - we discover new species every year

Question 30

Golden age of species recovery

Answer 30

What we’re in now, but biodiversity is under a threat globally

p.s. 25% of all known amphibian species were discovered in the last 10 years, since 93 the # of known mammal species increased by 10%

Question 31

How can we conclude we’re in the most diverse point in time

Answer 31

By combining statistics, the fossil record, and current known numbers of species

Question 32

Majority of new animals being discovered are

Answer 32

insects (mostly beetles)

Question 33

6th major extinction event fun facts

Answer 33

• we’re in it

- rate of extinction is now 100 times greater than naturally, by some estimates