Class Reptilia

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Class Reptilia
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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.

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Class Reptilia

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

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Ectothermic
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Common Features

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

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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.

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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.

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Common features

• Excretory waste uric acid (doesnt 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.

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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.

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Amniote Egg
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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.

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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.

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Reptile Skulls

• Anapsid
• No opening
• Synapsid
• One opening
• Diapsid
• Two openings
• Euryapsid
• One small opening

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Subclass AnapsidaOrder 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

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Primitive features

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

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Subclass AnapsidaOrder Testudines

• All lay eggs on land.
• Third eyelid nictitating membrane.
• Longest living vertebrates (100years in wild)!

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TURTLES TORTOISES

• Only reptile with shell
• Only reptile WITHOUT TEETH

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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-t
ortoise.jpg
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Turtle Shell
Carapace
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Plastron
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Box TurtleTerrapene

• Adapted to live on land
• Feet not webbed
• High domed shell
• Safe

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Red-Eared SliderTrachemys

• Red stripe behind eye
• Live in or near water
• Ponds
• Slow moving water
• Pets
• Carry Salmonella

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Snapping TurtleChelydra

• Live in water
• Lay eggs on land
• Long tail
• Muscular limbs

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Giant TortoiseLifespan 150 Years
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Leatherback Sea Turtle

• 6 feet long
• 1,400 pounds

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Diapsids

• Dinosaurs
• Snakes
• Lizards
• Crocodilians
• Birds

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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

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Order Rhynchocephalia

• 2 species of Tuatara
• Solitary, nocturnal, burrowing animal

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Order Squamata

• Kinetic skull
• Movable joints
• Lizards
• Snakes
• Dinosaurs

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Order Squamata

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

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Geckos

• Small lizards
• Adhesive toe pads

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Gecko Toe Pads
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Wall LizardLacerta

• Color is variable
• Slender body
• Small scales

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AUTOTOMY

• Self amputation to escape predators
• Cant regrow
• Costly lose muscle/stored fat

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http//www.californiaherps.com/lizards/images/ecpr
incipis1dn.jpg
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Texas Horned Lizard

• Spines for protection
• Eats ants
• Endangered species

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Gila Monster

• Poisonous lizard
• Not very aggressive

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Green Iguana

• Ornamental crest
• Five feet long
• Tropical rainforest
• Mexico
• South America
• Omnivores

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Chameleons

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

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Komodo Dragon

• Attack and eat humans
• 10 feet long
• 300 pounds
• Indonesia

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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

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Snakes

• No legs
• No external ears
• Jacobsons organ
• Sense smell with aid of tongue
• Cornea of eye protected with a spectacle
• transparent membrane
• Skull bones loose
• Swallow large prey

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JACOBSONs ORGAN

• 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

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http//www.kwic.com/pagodavista/schoolhouse/speci
es/herps/snktonge.htm
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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

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http//www.kwic.com/pagodavista/schoolhouse/speci
es/herps/snktonge.htm
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Swallow Prey
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Constrictors
http//www.thematzats.com/snakes/images/squeeze.gi
f

• Wrap around prey and kill by suffocation
• Ex Boa constrictors

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http//www.eastrock.org/brazil/images/bra19.jpg
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VIPERS

• Inject venom with large movable fangs
• Ex rattlesnakes, copperheads, water moccasins

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Images from http//www.worsleyschool.net/science
/files/rattle/snakes.html
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ELAPIDS

• Inject venom with small fixed (non-movable)
  fangs
• Ex cobras, kraits, coral snakes

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http//www.kidsturncentral.com/animals/cobra.htm
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Snake Venom
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Copperhead Agkistrodon
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Cottonmouth or Water Moccasin Agkistrodon
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Western Diamond Backed RattlesnakeCrotalus
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Prairie Rattlesnake Crotalus
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Timber Rattlesnake Crotalus
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Black Rat Snake
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Diamond Backed WatersnakeNerodia
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Green Snake
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Coral Snake
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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

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• 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

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Dinosaurs
Dominate animals in Mesozoic Era
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Euryapsid

• Extinct
• Ichthyosaurs

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Synapsids

• Pelycosaurs
• Dimetrodon
• Mammal like reptile

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Order Crocodilia

• Crocodiles
• Caimans
• Alligators
• Gavials
• Elongated skull
• Four chambered heart

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Alligator
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Caiman

• Elevated eyes

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Gavial
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Alligator
Caiman
Crocodile
Gavial
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The End
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