Lecture 7 Flashcards

0
Q

Why were plants a good source of energy 365mya?

A

They were abundant, an unexploited energy source with no competition

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1
Q

What was the food chain for early tetrapods based upon?

A

The aquatic system of carnivory

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2
Q

What challenge faced animals who wanted to use plants as an energy source?

A

Cellulose

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3
Q

Why couldn’t early terrestrial animals digest cellulose?

A

It is composed of beta glucose which they were unable to digest.

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4
Q

How did the synapsids jaw make it difficult for them to break down plant matter?

A

Sharp cone teeth which lacked dental occlusion
Jaw composed of several bones
Temporal fenestra was in line with lower jaw

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5
Q

When did the synapsids walk the earth?

A

300mya

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6
Q

How did the early cynodonts adapt to breakdown plant matter?

A

They acquired dental occlusion by changing the shape of their teeth
Their temporal fenestra was raised to increase jaw strength

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7
Q

When did the early cynodonts roam the earth?

A

260mya

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8
Q

How did the late cynodont adapt to mechanically breakdown plant matter?

A

Jaw articulation by two bones
Complex cusp pattern of molars and premolars
Temporal fenestra located above mode of action

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9
Q

When did the late cynodonts roam the earth?

A

195mya

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10
Q

What are the role of incisors?

A

Pincers for grasping or grooming

Elongated chisels for gnawing

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11
Q

What is the function of canines?

A

Elongated to stab and hold prey

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12
Q

What is the function of molars in carnivores?

A

Carnissal teeth

Slicing and tearing flesh

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13
Q

What is the function of the molars in the herbivores?

A

Grinding

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14
Q

What are the selenodonts?

A

Molars with crescent shaped ridges

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15
Q

What are the lophodonts

A

Molars with ridges between cusps

16
Q

What are the loxodonts?

A

Molars with extreme lophodont ridges

17
Q

What are the four points on a molar?

A

Metacone
Hypocone
Paracone
Protocone

18
Q

What type of teeth are common in browsers?

A

Brachydont teeth which have low crowns and finite growth

19
Q

What time of teeth are common in grazers?

A

Hysodont which are high crowned teeth which are constantly growing

20
Q

How have insects adapted to breakdown cellulose?

A

They have developed endosymbiont relationships with bacteria that can break down cellulose by consuming them.

21
Q

How have tetrapods evolved to digest cellulose?

A

They have developed an endosymbiotic relationship by consuming the required microorganisms or consuming insects containg the required microorganisms

22
Q

Describe hindgut fermentation

A

The caecum has been enlarged ti allow faster digestion
Fermentation of cellulose by microorganisms
Cellulose utilisation is 45%
Suits high starch food
Suits low energy food

23
Q

Describe foregut ruminants

A
Enlargement of foregut and additional mechanical breakdown
Cheing the cud
Longer digestion 
60% cellulose abosrbed
Inefficient processing of starch
24
What is chewing the cud?
When contents are rechewed to further breakdown cellulose
25
Which method of fermentation do small mammals prefer?
Hindgut fermentation as need energy fast
26
What type of digestion do medium sized mammals prefer?
Foregut rumination
27
What type of digestion do very large mammals prefer?
Hundgut fermenters