Reptile Overview & Chelonians

Question 1

Give the ancestral group that have rise to the amniotes

Answer 1

Early Labyrinthodont amphibian

Sister clade to living amphibians

Question 2

Why did amniotes evolve ?

Answer 2

Due to the reproductive constraints placed on amphibians

Have to return to water for egg laying. (shell less eggs)

Question 3

What does the amniotic egg provide ?

Answer 3

An aquatic environment in the egg for offspring

Question 4

Amniotes still have a larval stage in life cycle

True or False ?

Answer 4

False, offspring hatch from the egg as mini adults.

Question 5

Describe the amniotic eggs of reptiles, birds and mammals.

Answer 5

Birds- calcareous
Reptiles- Leathery and flexible
Mammals- no longer egg shell, develops within the mother

Question 6

List the 4 extra-embryonic membranes of amniotic eggs.

Answer 6

Amnion
Chorion
Allantois
Yolk sac

Question 7

What is the purpose of the Amnion ?

Answer 7

A membranous sac surrounding the embryo in fluid.

Give protection

Question 8

What is the purpose of the Chorion ?

Answer 8

An outer membrane than surronds the embryo and yolk sac.

Allows gas exchange between embryo and air.

Question 9

What is the purpose of the Allantois ?

Answer 9

Outgrowth of the hindgut

Storage of nitrogenous waste (

Question 10

What is the purpose of the yolk sac ?

Answer 10

Surronds the yolk, giving an extensive blood supply to embryo

Question 11

Give the disadvantages of the amniotic egg

Answer 11

Air is more thermally variable than water- Parental care to maintain temperature

Must have internal fertilisation, Require organs for this to occur

Energetcially costly for fewer offspring.

Substances required have to e consumed. i.e CaCO3

Question 12

When did the divergence of synapsids (mammals) and reptiles occur ?

Answer 12

285 million years ago

Question 13

How could the early amniotes be distinguished ?

Answer 13

By the number of fenestra in the skull

Question 14

How would you identify…
Anapsid
Synapsids
Diapsids

Answer 14

Anapsid- No fenestra
Synapsids- 1 fenestra
Diapsids- 2 opening

Question 15

What were the parareptiles ?

Answer 15

Permian and Triassic reptiles
Large stocky quadrupeds
Plates on skin
Died 200 million years ago

Question 16

What are the chelonians ?

Answer 16

Turtles and tortoises

Question 17

Which ancestral amniote group did the chelonians evolve from ?

Answer 17

Modern day research suggests the diapsids (2 fenestra)

Question 18

Give the Chelonian adaptions to…
Seawater
Freshwater
Terrestrial

Answer 18

Seawater- Flippers for propulsion
Fresh- Webbed feet
Terrestrial- lost aquatic adaptions

Question 19

What is the benefit of webbed feet for a chelonian in a freshwater system ?

Answer 19

Chelonians will spend more time at the bottom of the water system hunting for food rather than swimming (flippers)

Question 20

Give the diet of Chelonians.

Answer 20

Carnivorous and Herbivorous

Question 21

Give the name for the top and bottom shell of a chelonian

Answer 21

Top- Carapace

Bottom- Plastron

Question 22

Give the 2 groups of Chelonian

Answer 22

Cyrptodires

Pleurodires

Question 23

What organisms are found witihin the Cryptodires ?

Answer 23

Most living turtles
Hidden neck turtle
Neck retracts in S shape into shell

Question 24

What organisms are found within the Pleurodies ?

Answer 24

Few species
Side necked turtle
Neck does not retract into shell