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20 Cards in this Set
- Front
- Back
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What is the difference between Sarcopterygians and Tetrapods?
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SARCOPTERYGIANS are osteichthyans that have a robust bony skeleton in appendages (fins or limbs).
TETRAPODS are sarcopterygians with 4 FEET, with fingers and toes, not fins. |
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What unites the group "Choanata"?
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The group is united by sharing CHOANAE (internal nostril).
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What is the function of a CHOANAE?
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The Choanae allows air to pass through external nostrils to lungs with the mouth closed.
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What is mosaic evolution?
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Mosaic Evolution is the concept that major evolutionary changes tend to take place in stages, not all at once.
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Name 3 characteristics of early the early tetropod "Acanthostega".
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1) Retain tail fin rays
2) Hand & foot polydactylous; (7 hind, 8 fore digits) 3) Gills 4) Limbs |
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Were the first tetrapods terrestrial or aquatic?
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1st tetrapods were AQUATIC—early tetrapod features not necessarily for living on land.
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Is 5 digits ancestral or derived in tetrapods?
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5 digits is NOT ANCESTRAL in tetrapods. Earliest tetrapods had 7 or 8 digits.
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What is a possible mechanism for getting 5 digits?
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Developmental truncation: If development is shortened, last features don’t appear.
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What are some feeding changes in early tetrapods?
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SKULL MOBILITY REDUCED because early tetrapods hunted in shallows, not surrounded by water so use biting / ram feeding in place of suction. Early tetrapods needed solid skull.
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How did hearing change in early tetrapods?
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HYOMANDIBULA changes function from skull flaring to hearing (as STAPES).
Stapes now connect skull to tympanic membrane (eardrum). The eardrum passes sound waves to brain. |
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How did early tetrapod stapes look/function?
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First stapes were big and chunky; vibrated slowly. They were bad for high pitch (frequency) sounds.
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Why did tetrapods invade land? (OLD IDEA)
Whats the problem with that idea? |
Early tetrapods escaped drying conditions in water.
The rock record shows no droughts in the Devonian. |
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Why did tetrapods invade land? (NEW IDEA)
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Exploration of novel food sources. (Invertebrates had already invaded land).
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Why did tetrapods invade land? (NEW NEWER IDEA)
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Go on land to heat up fast, then carry heat back to the water.
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What do you know about the Acanthostega?
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Highly aquatic early tetrapods.
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What do you know about Ichthyostega?
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Developed after Acanthostega. Developed more robust ribs, more robust girdle, and less tail fin.
• HOWEVER - The ear was suited for underwater hearing, and foot similar shape to seal flipper. (POSSIBLY SECONDARILY AQUATIC). |
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BATRACHOMORPHS include most taxa thought of as _______ and are distinguished by what?
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Amphibians.
Flat skull, no kinesis, and 4 or fewer fingers on hand. |
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Modern amphibians are included in _____, which are a derivation of _____.
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Temnospondyls.
Batrachomorphs. |
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What do you need to know about Reptilomorphs?
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Typically had deeper skull, more terrestrial, longer limbs, were among the FIRST TETRAPODS TO BECOME HERBIVORES. (Most carnivorous).
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What were some characteristics of the Paleozoic World?
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Continents converged to form supercontinent PANGAEA.
• No flowering plants. (Trees from ferns, horsetails, etc.) • Higher O2, giant insects. |
