13. Cold or Hot Flashcards

1
Q

What is a tetrapod?

A

A four-footed animal, especially vertebrates of all classes higher than fish

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2
Q

What is the significance of the Tiktaalik?

A

Could be a missing link between fish and amphibians, and where many typical features of tetrapods developed.

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3
Q

When approximately did Tiktaalik’s develop?

A

375ma, mid-devonian

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4
Q

What environmental factor of oceans at the time made amphibian development ‘necessary’?

A

Large areas of oxygen-poor, shallow regions in oceans
- Which were particularly hard for fish to survive in

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5
Q

What main 3 new attributes did the Tiktaalik develop/

A

Wide legs (for shallow regions), a neck, stronger fins

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6
Q

What early tetrapod with lungs and limbs developed around 370Ma?

A

Ichtyostega

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7
Q

What sort of amphibians were developing around 300Ma?

A

Reptile-like amphibians (somewhat like crocodiles)

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8
Q

How do warm-blooded animals use of resources compare to that of a cold-blooded animal?

A

They use approximately 10x more energy, oxygen, food

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9
Q

What were the conditions of the permian like?

A

Warmer and wetter

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10
Q

State the 3 main theories as to why warm-bloodedness developed despite its seemingly negative effects.

A
  • Mammals and birds were insulated
  • Size
  • For the metabolic rate
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11
Q

Explain why the insulation of mammals would allow/cause warm-bloodedness.

A

Insulation could cause internal temp to raise
- But generally, our insulation works because of our internal temp so would be hard to evolve in this direction

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12
Q

Explain why size of animals could cause warm-bloodedness

A

A shrinking of mammals (which took place around the time warm-bloodedness evolved) would reduce their ability to maintain internal body temp
- So they would need to increase their metabolism or have fluctuating body temp

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13
Q

Why might metabolism rates explain warm-bloodedness?

A

Mammals may have been evolving for higher metabolism (preferable for prey and predators) and internal heat was just a byproduct

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14
Q

What is the deciding factor between whether increased metabolism or dwarfing were the cause of warm-bloodedness?

A

When it took place; whether it was when mammals were still big and tropical, or once they were shrinking.

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15
Q

What piece of evidence is used to determine whether a mammal was hot or cold blooded?

A

Presence of respiratory turbinates
- A feature which allowed fast breathing effectively and are taken as evidence of sustained aerobic activity
Almost every warm-blooded mammal and bird has them now

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16
Q

When are respiratory turbinates first seen in the fossil record?

A

When therocephalians first evolve, approx 200Ma - pre dinosaur hegemony