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BSCI 1511 > History of Life > Flashcards

History of Life Flashcards

1
Q

How many years ago was this description accurate?: The prehistoric ocean was teeming with life. Living organisms had not yet ventured out onto land and the skies were absent of any birds, insects, or winged dinosaurs.

A

550 million years ago.

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2
Q

Which era is referred to as the age of fish?

A

Paleozoic

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3
Q

Which era is referred to as the age of dinosaurs and reptiles?

A

Mesozoic

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4
Q

Which era is referred to as the age of mammals?

A

Cenozoic

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5
Q

How is the geologic record divided?

A

The Hadean, Archaean, Proterozoic, and Phanerozoic eons (the last half billion years).

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6
Q

How is the Phanerozoic eon divided?

A

Into three eras: the Paleozoic, Mesozoic, and Cenozoic.

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7
Q

The fossil record is biased in favor of species that:

A
  1. Existed for a long time
  2. Were abundant and widespread
  3. Had hard parts
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8
Q

What is the first step in the sequence of life’s origination?

A

Abiotic synthesis of small organic molecules such as amino acids and nucleotides.

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9
Q

What is the second step in the sequence of life’s origination?

A

The joining of these smaller molecules into macromolecules, such as proteins and nucleic acids.

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10
Q

What is the third step in the sequence of life’s origination?

A

The packaging of these macromolecules into protocells (droplets with membranes that maintained a different internal chemistry).

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11
Q

What is the fourth step in the sequence of life’s origination?

A

The origin of self-replicating molecules that eventually made inheritance possible.

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12
Q

What happened about 3.5 bya?

A

The first single-celled organisms. Prokaryotes were earth’s sole inhabitants for more than 1.5 billion years.

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13
Q

What are the oldest known fossils? How old are they?

A

The oldest known fossils–dating back some 3.5 billion years–are stromatolites, rocks formed by the accumulation of sedimentary layers on bacterial mats.

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14
Q

What was happening 2.7 bya?

A

Most atmospheric O2 is of biological origin. By 2.7 bya, it began accumulating in the atmosphere and rusting iron-rich terrestrial rock.

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15
Q

What was the oxygen revolution? When did it occur?

A

The oxygen revolution (2.7-2.3 bya) caused the extinction of many prokaryotic groups. Some groups survived and adapted using cellular respiration to harvest energy.

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16
Q

How old are the oldest fossils of eukaryotic cells?

A

1.8 billion years.

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17
Q

What does endosymbiosis attempt to explain?

A

The origin of eukaryotic cells.

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18
Q

What does endosymbiosis posit?

A

Mitochondria and plastids were formerly free-living prokaryotes that began living within larger cells, eventually giving rise to eukaryotic cells.

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19
Q

How old are the oldest known fossils of multicellular eukaryotes that can be resolved taxonomically?

A

They are of small algae that lived about 1.2 bya.

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20
Q

When do larger and more diverse multicellular eukaryotes appear in the fossil record?

A

About 600 mya–multicellularity in these lineages evolved independently, giving rise to plants, fungi, and animals.

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21
Q

What is the Cambrian explosion?

A

The Cambrian explosion refers to the sudden appearance of fossils resembling modern animal phyla within a ~10 million year window of the Cambrian period. This is where the first evidence of predator-prey interactions in the fossil record were found.

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22
Q

What is the range of the Precambrian period?

A

4.5 bya - 543 mya

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23
Q

When did animals with hard outer parts evolve?

A

During the Cambrian period. As a result, many of these shells became fossilized.

24
Q

When did the first tectonic plates form?

A

During the precambrian period.

25
Q

What does the Ordovician fossil record contain?

A

A diversity of marine invertebrates and conodonts (early vertebrates).

26
Q

When was the Ordovician period?

A

490 - 443 mya

27
Q

When was the Silurian period?

A

443 - 417 mya

28
Q

When did the first coral reefs appear?

A

The Silurian period

29
Q

When did jawless fish diversify and the first fish with jaws appeared?

A

The Silurian period

30
Q

What period is the earliest good evidence of life on land found?

A

The Silurian period

31
Q

When did small vascular plants evolve? Where did they live?

A

The Silurian period. Tiny vascular plants that grew in moist areas near the shore and long rivers and streams appeared then.

32
Q

What are some of the first animals to transition to land? When did this occur?

A

Centipedes and scorpions. The Silurian period

33
Q

When did placoderms reach their greatest diversity? What are they?

A

Placoderms–armored fish with bony plates in their mouths instead of teeth–reached their greatest diversity during the Devonian period.

34
Q

When was the Devonian period?

A

417 -354 mya.

35
Q

When did armored jawless fishes become abundant?

A

In the Devonian period.

36
Q

When did early Chondrichthyes (sharks and rays) appear?

A

In the Devonian period.

37
Q

When did the first ray-finned and lobe-finned fishes appear?

A

In the Devonian period.

38
Q

Which two major animal groups colonized the land In the Devonian period?

A
  1. Tetrapods: four-limbed, land-living vertebrates
  2. Terrestrial arthropods, including wingless insects and the earliest arachnids.
39
Q

Describe the environment of the Carboniferous period.

A

Vast swamps formed over low-lying areas of North America, northern Europe, and Asia during the Late Carboniferous. The lush vegetation of these swamps became coal through chemical and physical processes associated with low-oxygen conditions, rapid burial, and subsequent metamorphism.

40
Q

When was the Carboniferous period?

A

354 - 290 mya

41
Q

When did the amniote egg emerge, and why was it significant?

A

During the Carboniferous period. It allowed the ancestors of birds, mammals, and reptiles to reproduce on land and the first reptiles (330 mya).

42
Q

When was the Permian period?

A

290 - 248 mya.

43
Q

When was the largest mass extinction in earth’s history?

A

During the Permian period. Nearly 90% of all species became extinct at the end of the Permian.

44
Q

What happened as the climate became drier in the Permian period?

A

The vast swamps of the Carboniferous disappeared and were replaced by forests more tolerant of dry conditions. Modern conifers first appeared in the fossil record of the Permian.

45
Q

What are the three time periods within the Mesozoic?

A
  1. Triassic
  2. Jurassic
  3. Cetaceous
46
Q

What did dinosaurs do during the Triassic period?

A

They made their first appearance and diversified to dominate the terrestrial faunas for the next 180 million years.

47
Q

When did the pterosaurs (the earliest flying vertebrates) evolve?

A

During the Triassic period.

48
Q

When did ichthyosaurs and plesiosaurs live?

A

The Triassic period.

49
Q

When did mammals first evolve?

A

The Triassic period.

50
Q

What happened at the end of the Cretaceous period?

A

One of the most famous mass extinctions in the history of life on earth. It has been estimated that perhaps 60-70% of all marine species and nearly 15% of all terrestrial genera, including many mammals, went extinct at the end of the Cretaceous. Perhaps the most famous victims were the dinosaurs–only their descendants, the birds, survived.

51
Q

When did the mass extinction of the dinosaurs occur?

A

About 65 mya.

52
Q

What happened to mammals after the extinction of terrestrial dinosaurs?

A

Mammals underwent an adaptive radiation. The disappearance of dinosaurs (except birds) allowed for the expansion of mammals in diversity and size.

53
Q

Besides mammals, what other notable radiations occurred in the wake of the dinosaur mass extinction?

A

Photosynthetic prokaryotes, large predators in the Cambrian, land plants, insects, and tetrapods.

54
Q

What happens during the Paleocene period?

A

Post K/T impact world (abiotic event)
Species recovery and mammalian radiations (biotic response)
Warming world–especially PETM (geologically instantaneous warming, methane hydrates, abiotic)
Change in flor and fauna.

55
Q

What happens during the Eocene period?

A

Early Eocene climatic optimum (abiotic event): mammalian radiations, tropics at high latitudes (biotic response)
Post K/T impact world (abiotic event)
Whale evolution: open niche space (biotic response)
Eocene cooling (abiotic): extinction of marine organisms, ungulates diversity increases, primates decline.

56
Q

What happens in the Oligocene period?

A

Opening of the drake passage (potential Eocene, abiotic event)
Dramatic cooling results in changes in marine and terrestrial diversity, although more extinctions occurred earlier in Eocene (biotic response).

57
Q

What happens in the Miocene period?

A

Warmer Miocene world (abiotic event): increased traffic on Bering Land Bridge, leading to mass migration between North America and Eurasis (biotic response)
Potential decline in CO2 levels -> decline in primary productivity, transition from browsers to grazers -> grassland expansion -> O2 grassland expansion globally

BSCI 1511 (32 decks)

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