1. KINGDOM ANIMALIA Phylum Chordata Subphylum Vertebrata Class Reptilia

2. Vertebrate Classes

3. History
Reptiles are the evolutionary base for the rest of the tetrapods.
Early divergence of mammals from reptilian ancestor.
Early reptiles arose from amphibian ancestor and were small, lizard-like insectivores.

5. Common Features
Positioning of legs more directly under animal (more support).
Paired limbs with five toes.
Adapted for running, climbing, swimming.
Absent in snakes.

6. Common Features
Body covered with horny epidermal scales made from protein keratin.
Scales serve to reduce water loss and provide protection.
Reptiles molt as they grow.
Jaws adapted to biting/tearing.

7. Story About the Crocodile Heart
Common features
Respiration through internally protected and moistened (a moist cloacal surface in some turtles).
Most reptiles have a 3-chambered heart with a partially divided ventricle.
No mixing of blood from lungs with deoxygenated blood.
Crocodiles have 4 chambers and a unique feature: cog teeth.
Story About the Crocodile Heart

8. Common features Excretory waste = uric acid (doesn’t waste water)
Brain = first cerebral cortex (capable of reasoning, planning, perception)
Still ectothermic
Must live in favorable conditions or hibernate.
Being ectothermic enables an organism to survive on much less food than an endothermic organism.

9. Reproduction
Internal fertilization: gametes not subject to desiccation.
Amniote egg = significant evolutionary breakthrough.
Egg covered by tough, water-resistant, leathery or calcerous shell.
Extraembryonic membranes compartmentalize the interior for several functions.

10. Amniote Egg

11. Amniote Egg
Chorion = hard covering permeable to respiratory gases but not water.
Allantois = functions in gas exchange and a storage reservoir for metabolic waste.
Amnion = fluid-filled sac acts as cushion for embryo and prevents desiccation.
Yolk sac = food for embryo; eliminates need for larval stage.

12. Reptile Skulls
Except for turtles, all reptiles have two temporal openings in the skull.
These openings have allowed for attachment and expansion of the jaw muscles.

13. Subclass Anapsida Order Testudines
260 species of turtles/tortoises
Oldest group of reptiles (225 mya)
Protective body shell
Encases vital organs
Provdes some protection to head/limbs
Composed of bony plates covered by horny epidermal scales
2 parts: upper carapace, lower plastron
Primitve features:
Loss of body-wall muscles
Ribs/trunk vertebrae fused to carapace
Lack teeth/horny beak grab and tear food

14. Subclass Anapsida Order Testudines
All lay eggs on land.
Third eyelid = nictitating membrane.
Longest living vertebrates (100+years in wild)!

15. Subclass Diapsida Superorder Lepidosauria Order Squamata
4675+ species of lizard
2700+ species of snakes
140 species of amphisbaenians
Limbless, burrowing animals
Vestigial eyes under skin
Order Rhynchocephalia
2 species of Tuatara
Solitary, nocturnal, burrowing animal

16. Order Squamata Most successful/diversified of living reptiles.
Occur in most habitats of world.
Snakes:
Elongated derivative of lizard (increased vertebrae, not lengthening of segments)
Lack limbs, eyelids, ear openings
Jaw bones are loosely united to allow swallowing of large prey
Throat and windpipe are at separate ends of mouth to allow breathing while eating
Can be venomous (hemotoxin/neurotoxin)
Tongue to smell, some have heat pits to sense body heat
Lizards:
Legs, eyelids, ear openings
Halves of lower jaw united

17. Superorder Archosauria
Includes extinct dinosaurs/pterosaurs and birds
23 species of crocodiles, alligators, & caimans
Largest of the living reptiles
Amphibious carnivores
Live in tropics/subtropics
Lizard-like body with short legs, clawed/webbed toes, massive tail
Flat head with nostrils at tip
Powerful jaws
Dorsal side armored with dermal plates