Amniotes and Lepidosaurs

Question 1

What are the key adaptations of tetrapods?

Answer 1

Air breathing

Limbs w/ fingers

Question 2

How do amniotes differ from amphibians + fish?

Answer 2

They have an amniotic egg

Question 3

Describe an amniotic egg

Answer 3

Egg encased in membranes

- protect egg from drying out + provide gas exchange

Question 4

How had reproduction changed on land?

Answer 4

Internal fertilisation

Often assisted by an intermittent organ
- penis in most
or hemipenes in lizards + snakes

Question 5

What is special about juvenile amniotes?

Answer 5

Loss of larval stage (no gills or fin)

= direct development

Question 6

Describe tetrapod skin

Describe amniotic skin

Answer 6

Lack bony scales
- can shed skin

This skin is waterproof
= keeps water in

Question 7

When did the 1st amniotes appear?

Answer 7

300+mya

Carboniferous

Question 8

Amniotes stage adaptive radiation.

What did the earliest amniotes differentiate into?

Answer 8

Synapsid lineage
(mammal)

Sauropsid lineage
(bird-reptile)

Question 9

Which lineage dominate in the late carboniferous –> permian?

Answer 9

Synapsids

-produced specialised herbivores + carnivores

Question 10

What enabled Sauropsids to take over + diversify?

Answer 10

Permo-triassic extinction wipes out synapsids

Question 11

Which groups make up Lepidosauria?

Answer 11

Tuataras
Lizards
Snakes

Question 12

What are tuataras?

Answer 12

Nocturnal
Inhabit cool environments in NZ
(Rats wiped them out on main island)
Specialised jaws w/ teeth that fuse to jawbone

Question 13

What are squamata?

Answer 13

Lizards + snakes
= most diverse tetrapod group
>ecologically diverse
>wide range of lifestyles

Question 14

What are the features of geckos?

Answer 14

>Lizards
>Day active 
>Specialised climbers
- use lamellae to stock to surfaces using intermolecular attraction 
> Caudal autonomy - grow new tail 
> flying geckos - elaborate falls + webs

Australian lost limbs + evolved snake-like body

Question 15

Where are iguanidae found?

Answer 15

1 species in Fiji

Few species in Madagascar

Question 16

What is special about marine iguanas?

Answer 16

Bask on hot lava rocks to raise body temp before diving into Pacific to feed

Question 17

Which group are chameleons in?

Answer 17

Acrodonts

Question 18

Why are chameleons among the most specialised lizards?

Answer 18

Opposable digits +
prehensile tail grasps branches

Change colour to blend in

Eyes elongated to increase magnification
- can independently swivel to track prey

Shoot out tongue to catch insects

Question 19

What are Amphisbaenia?

What are their features?

Answer 19

Worm lizards

> Specialised for burrowing
Worm-like bodies surrounded by ring of scales
Slide skin back + forth to crawl through narrow tunnels
Powerful jaws + a few large teeth
Reduced eyes + no external ears
- enlarged ear bones

Question 20

Give an example of an Anguimorpha

Answer 20

Komodo dragon

Question 21

When was there a mass extinction of lizards?

Answer 21

K-T boundary

Question 22

How do snakes feed?

Answer 22

All predators
- some prey is equal to or greater than their own body weight

Multiple cranial + mandibular hinges allow them to dislocate their faces to swallow large prey

Also have no sternum so rib cage can expand to swallow large prey

Question 23

How are snakes adapted to being carnivores?

Answer 23

Hooked teeth
Constriction - disables prey by cutting off blood supply to brain
Venom - cytotoxic + neurotoxic posions

Question 24

What are the 2 hypothesis for how the snake elongate body plan evolve?

Answer 24

Marine origins

Fossorial (true)

Question 25

Explain the marine origins hypothesis

Answer 25

Snakes could be related to long-bodied, marine mosasaurs

= suggests marine ancestry

Question 26

Explain the fossorial hypothesis

Answer 26

Loss of eyelids
Simplified eye
Loss of external ears
Long skinny body

Question 27

What is the oldest definitive snake?

What are its features?

Answer 27

Tetrapodophis

4 limbs (bridges gaps between snakes + lizards)
Large no. of vertebrae for constriction 
Large recurved teeth 
Elongate trunk relative to tail = typical of burrowing lizards

Question 28

How has snake feeding evolved?

Answer 28

Early snakes were carnivores + constrictors

Question 29

Where did early snakes come from?

Answer 29

Gondwana

= ancient dinosaur-era continent