1. Amphibians Reptiles Mammals (not in this show)
Vertebrates:
Amphibians
Reptiles
Mammals (not in this show)

2. Overview: Half a Billion Years of Backbones
By the end of the Cambrian period, some 540 million years ago
An astonishing variety of animals inhabited Earth’s oceans
One of these types of animals
Gave rise to vertebrates, one of the most successful groups of animals

3. The animals called vertebrates include the groups: fish, amphibian, reptiles, birds & mammals
Get their name from vertebrae, the series of bones that make up the backbone

4. The Origin of Tetrapods
In one lineage of lobe-fined fish:
The fins became progressively more limb-like while the rest of the body retained adaptations for aquatic life
Tetrapod limb skeleton
Bones supporting gills
Figure 34.19

5. Amniotes
Amphibians
Greerpeton
Hynerpeton
lchthyostega
Acanthostega
Metaxygnathus
Elginerpeton
Eusthenopteron
Panderichthys
Lungfishes
Coelacanths
Ray-finned fishes
Paleozoic
Silurian
Devonian
Carboniferous
Permian
To present
420
415
400
385
370
355
340
325
310
295
280
265
Millions of years ago

6. Amphibians & Reptiles: Eukaryotic: Multicelullar Heterotrophic
Animals (so they can move on their own)
Have an Endoskeleton: skeleton is inside the body. Opposite case with: Insects, Arachnids, Scorpions: Exoskeleton (No bones, just hardened outer tissues)

7. Amphibians & Reptiles:
Both are Ectotherms (opposite is endotherms like mammals)
Ectothermic (“outside heat”) they depend on external sources of heat to help keep their body temperature up
Means that:
Body
Temp
Environment
COLD HOT
ECTO
ENDO
Amphibians & Reptiles have a slower Metabolism than mammals:
So they can go longer w/o
Food (weeks in some cases)

8. Amphibians: (frogs, toads, salamanders, newts) always live near water*
Have thin slimy skin that dries very fast & must be kept moist or they can easily die of dehydration
Lay their eggs in or near water sources
Some spend their entire life or part of it, in the water (tadpoles)

9. Eggs Amphibian Reproduction:
Their eggs lack the classic white shell of typical eggs.
Since the eggs are usually placed in water:
There is no need to prevent water loss OR to stand out (visually) to predators by dressing the egg up in shell
Eggs

11. (e) American alligator (Alligator mississipiensis)
Reptiles : bodies evolved for Water Conservation
Evolved thick scales around their bodies
Provided physical protection
Stopped water loss (but can still absorb heat from outside)
Body size can now be bigger w/o losing water
(amphibians never over 150lbs  more surface area = more water loss)
(e) American alligator (Alligator mississipiensis)

12. Overall Reptiles are adapted to be able to survive farther away from sources of water than most amphibians can.
No scales or claws

13. Reptiles: Evolved behaviors to get or maintain body heat:
Sunbathing (prefer rocks)
Dormant in Winter or…
Live where it is always hot (Tropics, Deserts)
No reptile or amphibians live at top of High Mountains or in Extreme Cold Climates like the Artic, Antarctic or Tundra
(b) Australian thorny devil lizard (Moloch horridus)

14. Reptile Reproduction:
Reptilian eggs have a strong leathery shell to protect the young and prevent dehydration
They will tear, but won’t crack like bird eggs
Most reptiles provide no parental care other than leaving the eggs in a safe spot (female crocs & possibly dinosaurs are exceptions)
Most reptiles lay 4 or more eggs at a time

15. Reptiles (that have legs) can lift their bodies off the ground
Movement
Heart anatomy
Being on land demands a lot more energy, so heart size and efficiency needs to increase to bring more O2 to body
Most amphibians will drag their stomachs when they “walk” or jump
2 chamber heart:
Fish
3 chamber hearts
Amphibians
Most Reptiles
4 chamber hearts
Some reptiles
Birds (flight)
Mammals
Reptiles (that have legs) can lift their bodies off the ground

17. Reptiles: the original large land carnivores
The majority of living reptiles are carnivores (only reptiles have claws, no amphibian has claws)
Some turtles and a few lizards are the only
reptilian herbivores
Reptilian herbivores may have teeth that are flatter or no true teeth at all

18. Reptilian Carnivores generally can’t shear or chew their food like mammals can, so they will either try to tear or rip it apart (croc “death-roll”) or will try swallow food whole (snakes)

19. Venom and Toxin Use
Snake
Skull