1
Synthesis Questions: Evolution and
Extinction Events Questions and
Answers (100% Correct Answers)
Already Graded A+
When did Synapsids evolve? Ans: In the Late Carboniferous
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period.
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How did the MIT group determine that a large igneous
Expert
province caused a mass extinction? Ans: They radiometrically
dated volcanic rocks from the Siberian Traps and showed
eruptions coincided with the end-Permian extinction.
What is a summary of the Devonian period? Ans: The Devonian
(419-359 Ma) is known as the 'Age of Fishes,' featuring the first
forests and flying insects, ending with the Late Devonian biotic
crisis.
What is a summary of the Carboniferous period? Ans: The
Carboniferous (359-299 Ma) is characterized by swamp forests,
an oxygen peak, giant insects, and the first amniotes.
What is a summary of the Permian period? Ans: The Permian
(299-252 Ma) saw the formation of Pangea, dominance of
synapsids, and ended with the Great Dying, the largest
extinction event.
What was the Late Devonian Biotic Crisis? Ans: It involved a
marine loss of approximately 50% of species, triggered by
ocean anoxia, volcanism, and climate cooling.
, 2
What was the End-Permian Extinction? Ans: The End-Permian
Extinction (252 Ma) was the greatest extinction event, with
about 84% of species lost, triggered by Siberian Trap
volcanism, anoxia, and ocean acidification.
What are the characteristics of Anapsid skull morphology?
Ans: Anapsid skulls have no temporal fenestrae, as seen in
turtles.
What are the characteristics of Synapsid skull morphology?
Ans: Synapsid skulls have one lower temporal fenestra,
© 2026 Assignment
exemplified by mammals.
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What are the characteristics of Diapsid skull morphology? Ans:
Expert
Diapsid skulls feature two temporal fenestrae, found in
reptiles, dinosaurs, and birds.
How did the expansion of vascular land plants in the Paleozoic
affect atmospheric oxygen and carbon dioxide levels? Ans: The
expansion during the Carboniferous lowered CO₂ and raised O₂,
leading to global cooling and supporting large insects.
What is Darwin's 'abominable mystery'? Ans: It refers to the
sudden appearance and rapid diversification of flowering
plants (angiosperms).
What key traits made angiosperms more successful than
gymnosperms? Ans: Key traits include flowers for efficient
reproduction, enclosed seeds, and coevolution with insects.
What are the 'Deadly Trio' of kill mechanisms in the end-
Permian and end-Triassic mass extinctions? Ans: The Deadly
Trio consists of global warming, ocean acidification, and
marine anoxia.
, 3
What are three traits evolved in Homo sapiens during the
Paleozoic? Ans: 1. Notochord: A flexible rod that develops into
the backbone. 2. Jaws: Evolved from skeletal rods supporting
gills, allowing for food processing. 3. Amniotic Egg Structures:
Protect embryos on land, freeing reproduction from water.
What character makes Dimetrodon more closely related to
humans than dinosaurs? Ans: Dimetrodon has synapsid skull
morphology with one lower temporal opening, a feature shared
with mammals, indicating a more recent common ancestor.
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What major changes occurred to life in the oceans during the
Mesozoic? Ans: Increased predatory pressure, rise of
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burrowing and armored animals, and the Mesozoic Marine
Expert
Revolution led to modern ocean ecosystems.
What changes occurred in phytoplankton during the Mesozoic?
Ans: There was an evolution and dominance of dinoflagellates,
coccolithophores, diatoms, and foraminifera, which were
crucial for carbon cycling and ocean chemistry.
What are the major changes we see to life on land during the
Mesozoic? Ans: This section is not provided in the notes, but
typically includes the rise of flowering plants, dinosaurs, and
mammals.
What major groups originated during the Mesozoic Era? Ans:
Dinosaurs, pterosaurs (flying reptiles), mammals, lizards, and
snakes.
What significant plant development occurred in the Cretaceous
period? Ans: The rise of flowering plants (angiosperms)
reshaped plant communities and drove insect coevolution.
What was the climate like during the early Mesozoic? Ans: Very
hot, greenhouse conditions with no polar ice caps.
, 4
How did the breakup of Pangea affect the climate? Ans: It
reshaped ocean currents and climate.
What were the effects of rising sea levels during the Mesozoic?
Ans: Flooded interiors of continents, created new shallow
marine habitats, and changed biodiversity patterns.
What is the first fossil evidence period for Chordates? Ans:
Cambrian period.
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What key character is associated with Chordates? Ans:
Notochord and dorsal nerve cord.
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In which period did Gymnosperms first appear? Ans: Devonian
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period.
What is a key characteristic of Gymnosperms? Ans: Seeds
without fruit and wind pollination.
What is the defining feature of Protostomes? Ans: Mouth
develops before anus during development.
When did Gnathostomes first appear in the fossil record? Ans:
Silurian period.
What is the key characteristic of Gnathostomes? Ans: Jaws.
What is the first fossil evidence period for Vascular Plants?
Ans: Silurian period.
What key feature do Vascular Plants possess? Ans: Vascular
tissues (xylem/phloem).
Synthesis Questions: Evolution and
Extinction Events Questions and
Answers (100% Correct Answers)
Already Graded A+
When did Synapsids evolve? Ans: In the Late Carboniferous
© 2026 Assignment
period.
Guru01 - Stuvia
How did the MIT group determine that a large igneous
Expert
province caused a mass extinction? Ans: They radiometrically
dated volcanic rocks from the Siberian Traps and showed
eruptions coincided with the end-Permian extinction.
What is a summary of the Devonian period? Ans: The Devonian
(419-359 Ma) is known as the 'Age of Fishes,' featuring the first
forests and flying insects, ending with the Late Devonian biotic
crisis.
What is a summary of the Carboniferous period? Ans: The
Carboniferous (359-299 Ma) is characterized by swamp forests,
an oxygen peak, giant insects, and the first amniotes.
What is a summary of the Permian period? Ans: The Permian
(299-252 Ma) saw the formation of Pangea, dominance of
synapsids, and ended with the Great Dying, the largest
extinction event.
What was the Late Devonian Biotic Crisis? Ans: It involved a
marine loss of approximately 50% of species, triggered by
ocean anoxia, volcanism, and climate cooling.
, 2
What was the End-Permian Extinction? Ans: The End-Permian
Extinction (252 Ma) was the greatest extinction event, with
about 84% of species lost, triggered by Siberian Trap
volcanism, anoxia, and ocean acidification.
What are the characteristics of Anapsid skull morphology?
Ans: Anapsid skulls have no temporal fenestrae, as seen in
turtles.
What are the characteristics of Synapsid skull morphology?
Ans: Synapsid skulls have one lower temporal fenestra,
© 2026 Assignment
exemplified by mammals.
Guru01 - Stuvia
What are the characteristics of Diapsid skull morphology? Ans:
Expert
Diapsid skulls feature two temporal fenestrae, found in
reptiles, dinosaurs, and birds.
How did the expansion of vascular land plants in the Paleozoic
affect atmospheric oxygen and carbon dioxide levels? Ans: The
expansion during the Carboniferous lowered CO₂ and raised O₂,
leading to global cooling and supporting large insects.
What is Darwin's 'abominable mystery'? Ans: It refers to the
sudden appearance and rapid diversification of flowering
plants (angiosperms).
What key traits made angiosperms more successful than
gymnosperms? Ans: Key traits include flowers for efficient
reproduction, enclosed seeds, and coevolution with insects.
What are the 'Deadly Trio' of kill mechanisms in the end-
Permian and end-Triassic mass extinctions? Ans: The Deadly
Trio consists of global warming, ocean acidification, and
marine anoxia.
, 3
What are three traits evolved in Homo sapiens during the
Paleozoic? Ans: 1. Notochord: A flexible rod that develops into
the backbone. 2. Jaws: Evolved from skeletal rods supporting
gills, allowing for food processing. 3. Amniotic Egg Structures:
Protect embryos on land, freeing reproduction from water.
What character makes Dimetrodon more closely related to
humans than dinosaurs? Ans: Dimetrodon has synapsid skull
morphology with one lower temporal opening, a feature shared
with mammals, indicating a more recent common ancestor.
© 2026 Assignment
What major changes occurred to life in the oceans during the
Mesozoic? Ans: Increased predatory pressure, rise of
Guru01 - Stuvia
burrowing and armored animals, and the Mesozoic Marine
Expert
Revolution led to modern ocean ecosystems.
What changes occurred in phytoplankton during the Mesozoic?
Ans: There was an evolution and dominance of dinoflagellates,
coccolithophores, diatoms, and foraminifera, which were
crucial for carbon cycling and ocean chemistry.
What are the major changes we see to life on land during the
Mesozoic? Ans: This section is not provided in the notes, but
typically includes the rise of flowering plants, dinosaurs, and
mammals.
What major groups originated during the Mesozoic Era? Ans:
Dinosaurs, pterosaurs (flying reptiles), mammals, lizards, and
snakes.
What significant plant development occurred in the Cretaceous
period? Ans: The rise of flowering plants (angiosperms)
reshaped plant communities and drove insect coevolution.
What was the climate like during the early Mesozoic? Ans: Very
hot, greenhouse conditions with no polar ice caps.
, 4
How did the breakup of Pangea affect the climate? Ans: It
reshaped ocean currents and climate.
What were the effects of rising sea levels during the Mesozoic?
Ans: Flooded interiors of continents, created new shallow
marine habitats, and changed biodiversity patterns.
What is the first fossil evidence period for Chordates? Ans:
Cambrian period.
© 2026 Assignment
What key character is associated with Chordates? Ans:
Notochord and dorsal nerve cord.
Guru01 - Stuvia
In which period did Gymnosperms first appear? Ans: Devonian
Expert
period.
What is a key characteristic of Gymnosperms? Ans: Seeds
without fruit and wind pollination.
What is the defining feature of Protostomes? Ans: Mouth
develops before anus during development.
When did Gnathostomes first appear in the fossil record? Ans:
Silurian period.
What is the key characteristic of Gnathostomes? Ans: Jaws.
What is the first fossil evidence period for Vascular Plants?
Ans: Silurian period.
What key feature do Vascular Plants possess? Ans: Vascular
tissues (xylem/phloem).
