13. Cold or Hot Flashcards
What is a tetrapod?
A four-footed animal, especially vertebrates of all classes higher than fish
What is the significance of the Tiktaalik?
Could be a missing link between fish and amphibians, and where many typical features of tetrapods developed.
When approximately did Tiktaalik’s develop?
375ma, mid-devonian
What environmental factor of oceans at the time made amphibian development ‘necessary’?
Large areas of oxygen-poor, shallow regions in oceans
- Which were particularly hard for fish to survive in
What main 3 new attributes did the Tiktaalik develop/
Wide legs (for shallow regions), a neck, stronger fins
What early tetrapod with lungs and limbs developed around 370Ma?
Ichtyostega
What sort of amphibians were developing around 300Ma?
Reptile-like amphibians (somewhat like crocodiles)
How do warm-blooded animals use of resources compare to that of a cold-blooded animal?
They use approximately 10x more energy, oxygen, food
What were the conditions of the permian like?
Warmer and wetter
State the 3 main theories as to why warm-bloodedness developed despite its seemingly negative effects.
- Mammals and birds were insulated
- Size
- For the metabolic rate
Explain why the insulation of mammals would allow/cause warm-bloodedness.
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
Explain why size of animals could cause warm-bloodedness
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
Why might metabolism rates explain warm-bloodedness?
Mammals may have been evolving for higher metabolism (preferable for prey and predators) and internal heat was just a byproduct
What is the deciding factor between whether increased metabolism or dwarfing were the cause of warm-bloodedness?
When it took place; whether it was when mammals were still big and tropical, or once they were shrinking.
What piece of evidence is used to determine whether a mammal was hot or cold blooded?
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
