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Chapter 20 Reptiles

Chapter 20 Reptiles. Ms. Cox. Introduction. Class Reptilia Order Testudines or Chelonia -----Turtles Order Rhynchocephalia------------Tuataras Order Squamata------------------snakes, lizards, worm lizards Order Crocodilia-------------------crocodiles, alligators, caimans, gavials.

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Chapter 20 Reptiles

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  1. Chapter 20Reptiles Ms. Cox

  2. Introduction • Class Reptilia • Order Testudines or Chelonia -----Turtles • Order Rhynchocephalia------------Tuataras • Order Squamata------------------snakes, lizards, worm lizards • Order Crocodilia-------------------crocodiles, alligators, caimans, gavials.

  3. Evolutionary Perspective • I. It is believed that the earliest members of the reptile family were the first to have amniotic eggs. • A. Characteristics of amniotic eggs: • 1.Extraembronic membranes (protect the embryo from desiccation). • 2. cushion the embryo • 3. promote gas transfer • 4. store waste materials • 5. leathery or hard shells • 6. albumen cushions the embryo and provides moisture and nutrients • 7. yolk supplies food

  4. Amniotic Egg

  5. Basic Characteristics of the Reptile Group • 1. They have a skull with 1 surface for movement with the first neck vertebra • 2. respiration by lungs • 3. kidneys • 4. internal fertilization • 5. amniotic eggs • 6. dry skin with keratinized epidermal scales *****note there are 17 orders of reptiles, most extinct, 4 orders today.********

  6. NO not a chicken

  7. Order Testudines (Chelonia)Turtles • Roughly 225 species of turtles • Characteristics • 1.bony shell • 2. limbs articulating internally to the ribs • 3. keratinized beak rather than teeth • 4. hinge that allows the shell to open and close (head and legs to come in and out) • 5. 8 cervical vertebrae (which can curve into S shape which allows turtles head to be drawn in)

  8. Order Testudines (Chelonia)Turtles • 6. long life spans • (reach sexual maturity at 7-8 years, and live 14 years or more, some on the Galapagos Islands may live in excess of 100 years) • 7. oviparous (eggs are deposited outside the body) • Females use hind limbs to excavate nests in the soil. They lay eggs there and cover with soil. Usually laid in clutches of 5-100 eggs.

  9. Order RhynchocephaliaLizardlike Reptiles • Characteristics • 1. two rows of teeth on the upper jaw, and a single row on the lower jaw • ****gives them a bite that could decapitate a small bird***** • 2. widely distributed in New Zealand • 3. often fall prey to human influences and domestic animals • 4. oviparous (lay eggs outside the body) • 5. share underground burrows with seabirds • 6. venture out of their burrows at dusk and dawn to feed on insects or occasionally small vertebrates. • See picture on page 316, Figure 20.7

  10. Order Squamata • Broken down into: • Suborder Sauria – THE LIZARDS • Suborder Serpentes- THE SNAKES • Suborder Amphisbaenia- WORM LIZARDS

  11. Suborder Sauria – THE LIZARDS • Characteristics • 1. 3,300 species • 2. two pairs of legs • 3. upper and lower jaws unite anteriorly • 4. length varies from 1 centimeter to 3 meters • 5. live on surface substrates • 6. hide or live under rocks or logs • 7. some burrow or stay in trees • 8. deposit eggs under rocks or debris or in burrows • 9. can be oviparous, ovoviviparous, viviparous • Examples: Geckos, Iguanas, Gila Monster – the only venomous lizards known.

  12. Suborder Serpentes- The Snakes • Characteristics: • 1. 2,300 species of snakes • 2. 300 species are venomous • 3. Worldwide about 30-40,000 people die from snake bites, most of these are in Southeast Asia • 4. elongated • 5. lack limbs • 6. may have more than 200 vertebrae and pairs of ribs • 7. upper jaws are movable, loosely connected to lower jaw • 8. Narrowing of the body has resulted in: loss of left lung, displacement of gallbladder, the right kidney, and often the gonads. • 9. Most snakes are oviparous • 10. However the New World boas, garter snakes give birth to live young.

  13. Suborder Amphisbaenia- Worm Lizards • Characteristics: • 1. 135 species • 2. specialized burrowers of soil in Africa • 3. most are legless • 4. skulls are wedge or shovel shaped • 5. single median tooth in the upper jaw • 6. skin has ring like folds • 7. feed on worms and small insects • 8. oviparous

  14. Order Crocodilia • Characteristics: • 1. 21 species • 2. triangular eye openings for the eye openings • 3. laterally compressed teeth • 4. elongated snout • 5. nostrils are at the tip of the snout • 6. muscular, elongated tail that is laterally compressed tail for swimming • 7. food is swallowed whole • 8. the stomach is like a gizard, they swallow rocks and other objects to be used in breaking apart food and digestion • 9. oviparous, lay eggs outside body and build nests

  15. Locomotion

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