Bio 370 exam 2 QUESTIONS WELL
ANSWERED GRADED A+
Describe the traits and life histories of the extant Lepidosaurian clades - correct answer ✔✔
Sphenodonts (aka Tautara/Rhyncocephalia)
Only found on islands off of New Zealand
Have not changed in 220 million years
Diapsid skull (different from ancestral version, but plesiomorphy)
Two rows of teeth on upper jaw, one row of teeth on lower jaw : jaws close and then slide
forward to generate shearing
Parietal eye on top of head for sensing changes in light
Mostly nocturnal
Live in burrows (often near seabird colonies)
Carnivores that eat mostly invertebrates
Can take up to 1 year to hatch, 20 years to mature, can live to 100
Reproduce every few years, temp dependent sex determination
Describe how the continents have moved across the surface of the earth over geologic time -
correct answer ✔✔ The plates move from magma activity. In early paleozoic, Cambrian there
were two main plates: Gondwana (modern Africa, Australia, Antarctica, South Asia) and
Laurentia with Baltica and Siberia. Toward the end of the Silurian they came together in the
southern pole. Then they drifted and came together around 335 mya to form Pangea with large
areas near the equator. This existed for around 160 years and began breaking up during the
Jurassic. Today's plates include the Eurasian, Indo-Australian, North and South American,
African, Pacific, Cocos, Nazca (all ocean plates).
Explain the role of changing climates and environments on vertebrate evolution - correct
answer ✔✔ The earth has mostly been hotter than it is today. During Silurian, there were
,mosses, fungi and small arthropods and worms on land. Land vertebrates evolved during the
late Devonian when sea levels fell, there was ocean anoxia and an extinction event. By late
Devonian there were fern forests on land and arthropods though no flying insects; these were
carnivores or detrivores. This was when the tetrapod outgroups such as osteolepiformes and
ichthyostegids arose. In the carboniferous oxygen levels rose and we get both further
diversification of plants, with weathering-resistant plant tissue and evolution of winged insects
and huge insects. The lissamphibian outgroups, the temnospondyls and lepospondyls, arose at
this time. Amniote initial radiation happened in the Permian.
Causes of temperature change: - correct answer ✔✔ 10 million year cycle of solar radiation
change;
Milankovich cycles:
100,000 year cycle of eccentricity of orbit,
40,000 year cycle of tilt (obliquity of ecliptic),
20-odd thousand year cycle of precession
short-term CO2 variation affects temperature (methane and water vapor are also greenhouse
gases, but varies less).
Other changes - correct answer ✔✔ Oxygen concentration changes in both air and ocean.
Anoxia an issue in Devonian, P-T, and Triassic-Jurassic extinctions. During periods of higher
oxygen concentration, animals invaded land twice (arthropods and then vertebrates) and
insects and later mammals grew larger.
List the causes of the three big Paleozoic mass extinctions - correct answer ✔✔ Late Ordovican-
Silurian extinction
Late Devonian extinction
Permian-Triassic extinction
Late Ordovican-Silurian extinction - correct answer ✔✔ Continents moved to south pole
Drop in CO2 levels
, Glaciation/global cooling -> drop in sea level
Late Devonian extinction - correct answer ✔✔ ocean volcanism
Ocean anoxia
Drop in sea level
Large vascular plants (dumping nutrients into sea, causing anoxia)
Permian-Triassic extinction - correct answer ✔✔ Mass volcanism -> short term, rapid cooling
Release of methane -> long term, rapid warming
Formation of Pangaea -> loss of continental shelf habitat
Ocean anoxia
Hydrogen sulfide release -> toxic, uses up oxygen
Sea level fluctuations
Possible meteor impact
Describe the challenges and opportunities of living in the terrestrial environment - correct
answer ✔✔ Gravity
Viscosity
oxygen
water
temperture
energy
Gravity - correct answer ✔✔ Body mass support sand resistance to blood flow
Support for respiratory structures lacking
ANSWERED GRADED A+
Describe the traits and life histories of the extant Lepidosaurian clades - correct answer ✔✔
Sphenodonts (aka Tautara/Rhyncocephalia)
Only found on islands off of New Zealand
Have not changed in 220 million years
Diapsid skull (different from ancestral version, but plesiomorphy)
Two rows of teeth on upper jaw, one row of teeth on lower jaw : jaws close and then slide
forward to generate shearing
Parietal eye on top of head for sensing changes in light
Mostly nocturnal
Live in burrows (often near seabird colonies)
Carnivores that eat mostly invertebrates
Can take up to 1 year to hatch, 20 years to mature, can live to 100
Reproduce every few years, temp dependent sex determination
Describe how the continents have moved across the surface of the earth over geologic time -
correct answer ✔✔ The plates move from magma activity. In early paleozoic, Cambrian there
were two main plates: Gondwana (modern Africa, Australia, Antarctica, South Asia) and
Laurentia with Baltica and Siberia. Toward the end of the Silurian they came together in the
southern pole. Then they drifted and came together around 335 mya to form Pangea with large
areas near the equator. This existed for around 160 years and began breaking up during the
Jurassic. Today's plates include the Eurasian, Indo-Australian, North and South American,
African, Pacific, Cocos, Nazca (all ocean plates).
Explain the role of changing climates and environments on vertebrate evolution - correct
answer ✔✔ The earth has mostly been hotter than it is today. During Silurian, there were
,mosses, fungi and small arthropods and worms on land. Land vertebrates evolved during the
late Devonian when sea levels fell, there was ocean anoxia and an extinction event. By late
Devonian there were fern forests on land and arthropods though no flying insects; these were
carnivores or detrivores. This was when the tetrapod outgroups such as osteolepiformes and
ichthyostegids arose. In the carboniferous oxygen levels rose and we get both further
diversification of plants, with weathering-resistant plant tissue and evolution of winged insects
and huge insects. The lissamphibian outgroups, the temnospondyls and lepospondyls, arose at
this time. Amniote initial radiation happened in the Permian.
Causes of temperature change: - correct answer ✔✔ 10 million year cycle of solar radiation
change;
Milankovich cycles:
100,000 year cycle of eccentricity of orbit,
40,000 year cycle of tilt (obliquity of ecliptic),
20-odd thousand year cycle of precession
short-term CO2 variation affects temperature (methane and water vapor are also greenhouse
gases, but varies less).
Other changes - correct answer ✔✔ Oxygen concentration changes in both air and ocean.
Anoxia an issue in Devonian, P-T, and Triassic-Jurassic extinctions. During periods of higher
oxygen concentration, animals invaded land twice (arthropods and then vertebrates) and
insects and later mammals grew larger.
List the causes of the three big Paleozoic mass extinctions - correct answer ✔✔ Late Ordovican-
Silurian extinction
Late Devonian extinction
Permian-Triassic extinction
Late Ordovican-Silurian extinction - correct answer ✔✔ Continents moved to south pole
Drop in CO2 levels
, Glaciation/global cooling -> drop in sea level
Late Devonian extinction - correct answer ✔✔ ocean volcanism
Ocean anoxia
Drop in sea level
Large vascular plants (dumping nutrients into sea, causing anoxia)
Permian-Triassic extinction - correct answer ✔✔ Mass volcanism -> short term, rapid cooling
Release of methane -> long term, rapid warming
Formation of Pangaea -> loss of continental shelf habitat
Ocean anoxia
Hydrogen sulfide release -> toxic, uses up oxygen
Sea level fluctuations
Possible meteor impact
Describe the challenges and opportunities of living in the terrestrial environment - correct
answer ✔✔ Gravity
Viscosity
oxygen
water
temperture
energy
Gravity - correct answer ✔✔ Body mass support sand resistance to blood flow
Support for respiratory structures lacking
