16: Amniotes (Reptiles) Flashcards

1
Q

When do we see reptiles form?

A

Carboniferous Period, 350 million years ago

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2
Q

What are the three major branches?

A

Synapsida
Anapsida
Diapsida

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3
Q

When did the dinosaurs go extinct?

A

End Cretaceous

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4
Q

When did turtles appear?

A

Mesozoic

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5
Q

When was the earliest reptile fossil from?

A

315mya

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6
Q

What was the earliest reptile fossil?

A

Tracks showing 5 fingers and scales
Can see position of legs, how they moved
Hyolonomus Iyelli

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7
Q

Examples of anapsids

A

Stem reptiles
Turtles
Tortoises

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8
Q

Examples of euryapsids

A

Ichthyosaurs

Plesiosaurs

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9
Q

Examples of diapsids

A
Crocodiles
Snakes
Lizards
Pterosaurs
Dinosaurs
Birds
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10
Q

Examples of synapsids

A

Mammal-like reptiles

Mammals

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11
Q

What are Ichthyosaurs?

A

Thrived in the Mesozoic
Sea reptiles
Evolved from unknown land reptiles
Viviparous

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12
Q

Function of the shell

A

External protection
Interaction with environment
Permeable

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13
Q

Function of the chorion

A

Allows nutrients to pass between

Protection

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14
Q

Function of the allantois

A

Sac that facilitates respiration
Stores waste
As yolk sac empties, allantois fills
Fuses with chorion

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15
Q

Function of the amnion

A

Covers embryo when it forms

Fills with amniotic fluid, which protects embryo

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16
Q

Function of yolk sac

A

Nutrients for growth

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17
Q

Difference between fish/amphibian eggs and reptile

A

In fish/amphibians there is only one membrane

Called the embryonic (Vitelline) membrane

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18
Q

How many EXTRA skull holes do diapsids have?

A

2 on each side (4 in total)

19
Q

How many EXTRA skull holes do anapsids have?

A

0, just eye holes

20
Q

How many EXTRA skull holes do synapsids have?

A

1 on each side

21
Q

What are the skull holes called?

A

Fenestrae (single is fenestra)

22
Q

Early reptile anatomy

A

Larger humerus than sarcopterygians and primitive amphibians
5 digits
Longer radius and ulna
Can support own body weight

23
Q

Advantages of being a reptile

A

Free of water
Access to different food
Avoid predators in water
Egg safety

24
Q

Exaptations that reptiles needed to have before move to land

A

No metamorphosis- only grow
Lay eggs on land
Internal fertilisation

25
Early amphibian vs reptile movement
Larger hip and shoulder girdles Larger hind and forelimbs Stronger vertebral column Less bendy movement
26
Reptile characteristics
``` Keratinised scales Two sets of paired limbs, usually with 5 toes Lungs Ectothermic Internal fertilisation Amniotic eggs, no aquatic larval stage ```
27
Differences between reptiles and amphibians
Reptiles have tough, dry, scaly skin- so don't dessicate Copulatory organ Efficient jaws for biting, gripping Complex nervous system
28
Examples of fossil anapsids
Scutosaurus- ancestors of turtles | Proganochelys
29
Proganochelys features
Late Triassic 200mya Had a carapcace (shell) of 90cm
30
Features of turtles
``` Enclosed within carapace Long, flexible neck Small brain Oviparous Carnivorous ```
31
What did the turtle shell evolve from?
The ribs
32
How do turtles breathe without ribs?
Expiration: contraction of transversus, aided by pectoralis Inspiration: contraction of obliquus and serratus, creating negative pressure
33
What turtle can breathe out of its bum?
Elseya albagula
34
Example of a fossil diapsid
Petrolacosaurus First Diapsid From around 300mya Small sharp teeth
35
What is a Tuatara?
A lizard thing Shares features with Mesozoic animals Diapsid skull, 2 openings One of the slowest rates of morphological evolution in vertebrates
36
What are Squamata?
Lizard worms, lizards and snakes Extremely diverse Diapsids
37
Lizard characteristics
``` Movable eyelids Keen vision Normally not great hearing Semi-solid urine if live in hot and arid climates Ectothermic Eg. leopard gecko Sticky feet ```
38
Worm lizard characteristics
``` Walk backwards just as well as forwards No back limbs at all, some have forelimbs No visible eyes/ears- hidden under skin Eg. Black and white worm lizard Grow by increasing length, not diameter ```
39
How do worm lizards move?
Dig by compressing soil against the roof with their head | As size increases, work required to compress soil increases exponentially
40
Snake feature
Lack pectoral and pelvic girdles Ribs along length of body to increase rigidity Highly kinetic skull increases feeding options- mobile bones Cornea is protected by a membrane No external ears
41
What is the Jacobsen organ in snakes?
A richly innervated chemosensory epithelium on the roof of the mouth Forked tongue places particles on the organ Transmitted to brain 'Tastes' molecules in air
42
What are pits?
The most sensitive heat detection system known | Used for strike accuracy
43
Crocodile features
``` Largest living reptile Fresh or sea water Have salt glands Closest living relative to birds 64-68 teeth ```
44
Where do dinosaurs sit?
In between crocodiles and birds