1

Vertebrate Movement to LandSZ2- Students will explain

evolutionary history of animals over the history of life on earth.

• Tetrapods- Animals with 4 limbs– Amphibians– Reptiles– Birds– Mammals

• Evolved from fish

2

Transition from Sea to Land

3

•Coelacanth

4

Eusthenopteron

5

Panderichthys

6

Tiktaalik

7

Transitional TetrapodsSkull, teeth, limbs similar to lobe-

finned fish

IchthyostegaAcanthostega

9

11

Amphibians

12

Adaptations to live on land

• Gills are usually lost• Lungs function• Breathe through skin• Secrete mucus – Prevent dehydration– Aids in respiration

13

More Adaptations to live on land

• Skeleton – Fins evolve into limbs– Vertebral column

supports body underneath it

AIR IS NOT AS BOUYANT AS WATER.

14

Evolution of CirculationFish Amphibian

Kingdom AnimaliaPhylum ChordataSubphylum VertebrataClass Amphibia1st land vertebrates Ex: frogs, toads, & salamanders

Class Amphibia – “Double Life”frogs, toads, salamanders, & newts

Characteristics• “Double Life” -lives part of

its life in water and part on land

• Ectothermic- “outside heat”- body temp. regulated by environment

• no scales or claws• Have thin, moist skin

Egg- tadpole- adult• larvae are herbivores, adults carnivores • larva have tails to move in water• external fertilization with no parental care• lay eggs without shells in water

AMPHIBIAN METAMORPHOSIS

18

19

• Amphibian Body Plan– Bilateral symmetry– 3 chambered heart– Larvae breathe through gills; adults breathe

through lungs– Breathe through thin, moist skin (produces

mucus)– Changes from larva to adult through

the process of metamorphosis

Class AmphibiaOrder Anura

• Anura- an=without, ura= tail• Tailless• Hindlegs adapted for jumping and swimming• Tympanum (ear drum) and larynx well

developedEx. Frogs and toadsfrog dissection intro-http://www.kiz-oyunlari.com/files/file/kurbaga_ameliyat.swf

Class AmphibiaOrder Caudata

• Caudata- “have a tail”• Long tail• 2 pairs of limbsEx. Salamanders and newts

Class Amphibia:Order Gymnophiona(Apoda)

Gymnos- nakedophis- snake

live in tropicsElongated bodyLimblesscarnivores

Ex. Caecilians – “blind”-small eyes

Kingdom AnimaliaPhylum ChordataClass Reptilia

Ex: snake, turtle, lizards crocodile, dinosaurs

Reptilian Traits:3 chambered heart (except for crocodilians-4)Ectothermic endo vs. ectoPaired limbs with five toes and clawsTough, dry, scaly skin (horny epidermal scales)

Jaws adapted for crushing and grippingBreathe with lungsSolid nitrogen wastes - due to metanephredic kidneyLarge cerebrum as compared to rest if brain-

behaviors- 1. instinct 2. learned

Reptile Legs• Short tetrapods for

walking• Positioning of the

legs more directly under the animal. This position provided more support than the splayed arrangement of the Amphibian legs.

Reproduction:Internal fertilization (to avoid desiccation of

gametes), oviparousLay amniotic eggs on land- no dependence on

waterShells leathery, sometimes calcareous

Amniotic Egg Structures & Functions• Chorion provides a special hard covering that is permeable

to respiratory gases (O2 and CO2) while being impermeable to water vapor.

• Allantois is a storage reservoir for metabolic waste products such as nitrogenous compounds.

• Amnion is a fluid filled sac that acts as a cushion for the embryo and also prevents desiccation.

• Yolk sac contains food for the embryo, thus eliminating the need for a larval stage.

Phylum ChordataSubphylum Vertebrata

Class ReptiliaOrder Testudine:

Body in a bony case -dorsal carapace(top of shell) - ventral plastron(bottom of shell)Jaws with a horny beak, no teethVertebrae and ribs fusedEx. Turtles and tortoises

Turtle Shell Anatomy

Fusion of ribs, vertebrae, & carapace

Turtle Life Cycle

Phylum ChordataSubphylum VertebrataClass ReptiliaOrder Sphenodonta

• Primitive reptile• closely related to dinosaur• Looks like lizard• Diapsid skullEx. Tuatara- only living species

Phylum ChordataSubphylum VertebrataClass Reptilia

Order SquamataDiapsid skull with two temporal openings

Skin is shed with horny epidermal scales

Jacobson’s organ- sense of smell

Movable skin, kinetic skull

Poisonous- hemotoxins (blood) , neurotoxins(nervous system)

EX. Snakes and lizards

Lizards have movable eyelidsSnakes- descended from tetrapod ancestor

• Elongated massive skull• True, 4 chambered heart• crocodiles, alligators, and caimans

Phylum ChordataSubphylum VertebrataClass Reptilia

Order Crocodilia

CrocodiliansCrocodiles, Alligators,

Caimans, & Gavials

Gavial

Alligator

Crocodile

Caiman

Crocodilian Reproduction

• The temperature inside the nest of several crocodilian species decides the sex of the young. ~50-80 eggs

• If the nest temperature is 30ºC, females will hatch from all the eggs

• If the temperature is above 34ºC, all will be males.

• If the temperature is in between, there will be young of both sexes.

Land Adaptations for Reptiles

• Legs (tetrapods)• Lungs and more efficient circulatory system• Scales• Claws• Amniotic egg• The excretory waste of the reptiles is uric acid

unlike the dilute, water wasting ammonia in the urine of Amphibians