Lecutre 9

Question 1

What is the only physical evidence of organisms, their size, structure, morphology that lived in past environments?

Answer 1

fossils

Question 2

What are some of the different modes of preservation possible?

Answer 2

• permineralization (petrifaction)
• impressions
• compressions
• casts and moulds
• tracks
• original materials from amber, frozen dediments, and rapid burial of organisms

Question 3

What are the broad 2 things that fossil record of life can tell us?

Answer 3

• can tell us about evolutionary change, extinctions
• past climate change and other environmental changes (paleoecology)

Question 4

Where are fossils found?

Answer 4

• most are rare and localized because they are preserved only in special environments where deposition prevails over erosion, allowing some remains to be preserved.
• microfossils like pollen and spores are much more common in sediments but are not visible to the naked eye
• especially east to preserve are animals with HARD PARTS like bones, shells, and especially teeth, the heardest parts of the skeleton!
• in special conditions, insects, plants, and even soft-bodied animals can be preserves, along with microscopic pollen and spores

Question 5

Explain compression

Answer 5

• fossil flower with carbon film, and part/counterpart of waterstrider from Eocene of BC

Question 6

explain impression

Answer 6

• imprint of trilobite, no carbon film remains

Question 7

explain original tissue

Answer 7

• fossil pollen grain x1000 of a basswood tree, and a mosquito and parasitic ematoode fossil in amber

Question 8

What are 4 of the many hypotheses for cause(s) of the rapid diversification?

Answer 8

• rising oxygen levels (due to photosynthesis) allowed evolution of larger, more active animals. Aerobic respiration allows greater activity
• predators evolve: early animals from ediacaran appear to be sessile or slow filter feeders. Appearance of hard shells, exoskeletons, spines, and evidence of damage to prey suggest evolution of anti-predator adaptations
• new niches develop along with increasing diversity, creating more ecological opportunities to change
• Hox GENES diversify, affecting development of body forms, leading to adaptive radiation of experimental animal forms, with many now extinct

Question 9

what are hox genes

Answer 9

• master regulatory genes that turn other genes on and off
• small genetic changes can cause big morphological responses in EVO-DEVO

Question 10

What do extinctions also define?

Answer 10

boundaries

Question 11

What are the 5 big mass extinctions

Answer 11

1. end-ordovician extinction
2. late Devonian extinction
3. end-Permian extinction
   - two main types from fossils:
   – mass extinctions and background extinctions
4. late Triassic extinction
5. end-cretaceous extinction
   - dinosaurs 65-66 mya

Question 12

Whats mass and background extinctions

Answer 12

mass: dramatic, often sudden, with loss of many species, families, and higher taxonomic categories

background: due to predation, disease, normal environmental changes