Class Reptilia 1

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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. 3

Class Reptilia Scales Amniotic egg One occipital condyle Ectothermic Three chambered heart Alligators have 4 Claws 4

Ectothermic 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

Fig. 26.3 8

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. 9

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. 10

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. 11

Amniote Egg 12

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. 13

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. 14

Reptile Skulls Anapsid Synapsid Diapsid Euryapsid No opening One opening Diapsid Two openings Euryapsid One small opening 15

Fig. 26.5 16

Subclass Anapsida Order Testudines 260 species of turtles/tortoises Oldest group of reptiles (225 mya) Protective body shell Encases vital organs Provides some protection to head/limbs Composed of bony plates covered by horny epidermal scales 2 parts: upper carapace, lower plastron 17

Primitive features Loss of body-wall muscles Ribs/trunk vertebrae fused to carapace Lack teeth; hard beak grab and tear food

Subclass Anapsida Order Testudines All lay eggs on land. Third eyelid = nictitating membrane. Longest living vertebrates (100+years in wild)! 19

TURTLES & TORTOISES Only reptile with shell Only reptile WITHOUT TEETH http://www.perlgurl.org/archives/2006/05/hawaiian_honu_the_green_sea_turtle.html http://www.carcosa.net/jason/blog_images/2005/07/04/african-spurred-tortoise.jpg 20

Turtle Shell Carapace Plastron 21

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Box Turtle Terrapene Adapted to live on land Feet not webbed High domed shell Safe 23

Red-Eared Slider Trachemys Red stripe behind eye Live in or near water Ponds Slow moving water Pets Carry Salmonella 24

Snapping Turtle Chelydra Live in water Lay eggs on land Long tail Muscular limbs 25

Fig. 26.7 26

Giant Tortoise Lifespan 150 Years 27

Leatherback Sea Turtle 6 feet long 1,400 pounds 28

Diapsids Dinosaurs Snakes Lizards Crocodilians Birds 29

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 30

Order Rhynchocephalia 2 species of Tuatara Solitary, nocturnal, burrowing animal

Order Squamata Kinetic skull Movable joints Lizards Snakes Dinosaurs 32

Order Squamata Most successful, diversified of living reptiles. Occur in most habitats of world. Lizards: Legs, eyelids, ear openings Halves of lower jaw united 33

Geckos Small lizards Adhesive toe pads 34

Gecko Toe Pads Fig. 26.12 35

Wall Lizard Lacerta Color is variable Slender body Small scales 36

AUTOTOMY Self amputation to escape predators Can’t regrow Costly; lose muscle/stored fat http://www.californiaherps.com/lizards/images/ecprincipis1dn.jpg 37

Texas Horned Lizard Spines for protection Eats ants Endangered species 38

Gila Monster Poisonous lizard Not very aggressive 39

Green Iguana Ornamental crest Five feet long Tropical rainforest Mexico South America Omnivores 40

Chameleons Arboreal - live in trees Africa and Madagascar Catch insects with tongue 41

Komodo Dragon Attack and eat humans 10 feet long 300 pounds Indonesia 42

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

Snakes No legs No external ears Jacobson’s organ Sense smell with aid of tongue Cornea of eye protected with a spectacle transparent membrane Skull bones loose Swallow large prey 44

JACOBSON’s ORGAN Sharpens its sense of smell. An extrasensory organ in the roof of a snake's mouth Sharpens its sense of smell. Two hollow, highly sensitive saclike structures Allows it to track both prey and potential mates 45 http://www.kwic.com/~pagodavista/schoolhouse/species/herps/snktonge.htm

HEAT SENSING ORGAN “Pit" organ located between the eye and the nostril on each side of the head. Detects heat given off by warm-blooded prey 46 http://www.kwic.com/~pagodavista/schoolhouse/species/herps/snktonge.htm

Swallow Prey 47

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Constrictors Wrap around prey and kill by suffocation http://www.thematzats.com/snakes/images/squeeze.gif Constrictors Wrap around prey and kill by suffocation Ex: Boa constrictors 49 http://www.eastrock.org/brazil/images/bra19.jpg

VIPERS Inject venom with large movable fangs Ex: rattlesnakes, copperheads, water moccasins 50 Images from: http://www.worsleyschool.net/science/files/rattle/snakes.html

ELAPIDS Inject venom with small fixed (non-movable) fangs Ex: cobras, kraits, coral snakes 51 http://www.kidsturncentral.com/animals/cobra.htm

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Snake Venom 53

Copperhead Agkistrodon 54

Cottonmouth or Water Moccasin Agkistrodon 55

Western Diamond Backed Rattlesnake Crotalus 56

Prairie Rattlesnake Crotalus 57

Timber Rattlesnake Crotalus 58

Black Rat Snake 59

Diamond Backed Watersnake Nerodia 60

Green Snake 61

Coral Snake 62

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 63

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

Dinosaurs Dominate animals in Mesozoic Era 65

Euryapsid Extinct Ichthyosaurs 66

Synapsids Pelycosaurs Dimetrodon Mammal like reptile 67

Order Crocodilia Crocodiles Caimans Alligators Gavials Elongated skull Four chambered heart 68

Alligator 69

Caiman Elevated eyes 70

Gavial 71

Alligator Caiman Crocodile Gavial 72

The End Fig. 26.14 73