16: Amniotes (Reptiles)

Question 1

When do we see reptiles form?

Answer 1

Carboniferous Period, 350 million years ago

Question 2

What are the three major branches?

Answer 2

Synapsida
Anapsida
Diapsida

Question 3

When did the dinosaurs go extinct?

Answer 3

End Cretaceous

Question 4

When did turtles appear?

Answer 4

Mesozoic

Question 5

When was the earliest reptile fossil from?

Answer 5

315mya

Question 6

What was the earliest reptile fossil?

Answer 6

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

Question 7

Examples of anapsids

Answer 7

Stem reptiles
Turtles
Tortoises

Question 8

Examples of euryapsids

Answer 8

Ichthyosaurs

Plesiosaurs

Question 9

Examples of diapsids

Answer 9

Crocodiles
Snakes
Lizards
Pterosaurs
Dinosaurs
Birds

Question 10

Examples of synapsids

Answer 10

Mammal-like reptiles

Mammals

Question 11

What are Ichthyosaurs?

Answer 11

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

Question 12

Function of the shell

Answer 12

External protection
Interaction with environment
Permeable

Question 13

Function of the chorion

Answer 13

Allows nutrients to pass between

Protection

Question 14

Function of the allantois

Answer 14

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

Question 15

Function of the amnion

Answer 15

Covers embryo when it forms

Fills with amniotic fluid, which protects embryo

Question 16

Function of yolk sac

Answer 16

Nutrients for growth

Question 17

Difference between fish/amphibian eggs and reptile

Answer 17

In fish/amphibians there is only one membrane

Called the embryonic (Vitelline) membrane

Question 18

How many EXTRA skull holes do diapsids have?

Answer 18

2 on each side (4 in total)

Question 19

How many EXTRA skull holes do anapsids have?

Answer 19

0, just eye holes

Question 20

How many EXTRA skull holes do synapsids have?

Answer 20

1 on each side

Question 21

What are the skull holes called?

Answer 21

Fenestrae (single is fenestra)

Question 22

Early reptile anatomy

Answer 22

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

Question 23

Advantages of being a reptile

Answer 23

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

Question 24

Exaptations that reptiles needed to have before move to land

Answer 24

No metamorphosis- only grow
Lay eggs on land
Internal fertilisation

Question 25

Early amphibian vs reptile movement

Answer 25

Larger hip and shoulder girdles
Larger hind and forelimbs
Stronger vertebral column
Less bendy movement

Question 26

Reptile characteristics

Answer 26

Keratinised scales
Two sets of paired limbs, usually with 5 toes
Lungs
Ectothermic
Internal fertilisation
Amniotic eggs, no aquatic larval stage

Question 27

Differences between reptiles and amphibians

Answer 27

Reptiles have tough, dry, scaly skin- so don’t dessicate
Copulatory organ
Efficient jaws for biting, gripping
Complex nervous system

Question 28

Examples of fossil anapsids

Answer 28

Scutosaurus- ancestors of turtles

Proganochelys

Question 29

Proganochelys features

Answer 29

Late Triassic
200mya
Had a carapcace (shell) of 90cm

Question 30

Features of turtles

Answer 30

Enclosed within carapace
Long, flexible neck
Small brain
Oviparous
Carnivorous

Question 31

What did the turtle shell evolve from?

Answer 31

The ribs

Question 32

How do turtles breathe without ribs?

Answer 32

Expiration: contraction of transversus, aided by pectoralis
Inspiration: contraction of obliquus and serratus, creating negative pressure

Question 33

What turtle can breathe out of its bum?

Answer 33

Elseya albagula

Question 34

Example of a fossil diapsid

Answer 34

Petrolacosaurus
First Diapsid
From around 300mya
Small sharp teeth

Question 35

What is a Tuatara?

Answer 35

A lizard thing
Shares features with Mesozoic animals
Diapsid skull, 2 openings
One of the slowest rates of morphological evolution in vertebrates

Question 36

What are Squamata?

Answer 36

Lizard worms, lizards and snakes
Extremely diverse
Diapsids

Question 37

Lizard characteristics

Answer 37

Movable eyelids
Keen vision
Normally not great hearing
Semi-solid urine if live in hot and arid climates
Ectothermic
Eg. leopard gecko
Sticky feet

Question 38

Worm lizard characteristics

Answer 38

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

Question 39

How do worm lizards move?

Answer 39

Dig by compressing soil against the roof with their head

As size increases, work required to compress soil increases exponentially

Question 40

Snake feature

Answer 40

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

Question 41

What is the Jacobsen organ in snakes?

Answer 41

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

Question 42

What are pits?

Answer 42

The most sensitive heat detection system known

Used for strike accuracy

Question 43

Crocodile features

Answer 43

Largest living reptile
Fresh or sea water
Have salt glands
Closest living relative to birds
64-68 teeth

Question 44

Where do dinosaurs sit?

Answer 44

In between crocodiles and birds