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Class Reptilia (Reptum = creep) CONQUEST OF LAND

Class Reptilia (Reptum = creep) CONQUEST OF LAND. Class Reptilia. First reptiles known from 280 million years ago, during the Permian period; greatest radiation of reptiles in Triassic (after the Permian) 230 million years ago, Mesozoic era (230-70 million years ago) age of dinosaurs;

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Class Reptilia (Reptum = creep) CONQUEST OF LAND

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  1. Class Reptilia (Reptum = creep) CONQUEST OF LAND

  2. Class Reptilia • First reptiles known from 280 million years ago, during the Permian period; • greatest radiation of reptiles in Triassic (after the Permian) 230 million years ago, • Mesozoic era (230-70 million years ago) age of dinosaurs; • died out in Cretaceous, about 70-80 million years ago

  3. Class Reptilia • Integument: • epidermis- very thin layer; • shed periodically • dermis- thicker • well developed, • has chromatophores; • contains scales- made of keratin same material as our hair

  4. Class ReptiliaFeatures that allowed them to conquer land • Cornified integument- dry scales • not homologous to scales of fishes- bony dermal • Keratin- same as hair and nails • protects against dessication

  5. Class Reptilia • Metanephritic kidney • have ureters that take urine directly to outside • able to conserve water by producing concentrated urine • excrete uric acid instead of urea or ammonia

  6. Class Reptilia • Amniotic egg; • which store all food necessary for development • and prevents water loss; • are covered by leathery or calcareous shell; • laid in sheltered areas on land • Consists of 4 membranes

  7. Class Reptilia • Amnion -("private pond")- • inner most membrane in egg • that forms a fluid filled sac around the fetus • Chorion - • the outer most membrane that surround the fetus; • in mammals it contributes to the placenta • Allantois - • a membrane around the fetus • that functions in respiration and excretion; • also plays important role in development of placenta in mammals • Yolk Sac - • membrane around the yolk (i.e., the food for the fetus) Amnion

  8. Class Reptilia • Reptilian jaw efficiently designed for crushing • jaws of fishes and amphibians designed for quick closure, • but jaws of reptiles designed for crushing prey

  9. Class Reptilia • Reptiles have some sort of copulatory organ permitting internal fertilization; • also associated with terrestrial existence • Reptiles have more efficient circulatory system and higher blood pressure; • crocodilians have a four chambered heart (first seen in vertebrates); • all other reptiles with three chambered heart • but it is more efficient in getting deoxygenated blood to lungs; • septum in ventricle separates blood that goes to lungs and body

  10. Class Reptilia • Reptiles lungs are better developed than those of amphibians- • amphibians had skin and gill respiration; • reptiles depend solely on lungs; • All reptiles, except limbless members, have better body support than amphibians; • more efficiently designed for travel on land

  11. Class Reptilia • Reptilian nervous system more advanced than amphibians; • some parts of brain (cerebrum) are enlarged; • sense organs well developed; • hearing is poorly developed; • 12 pairs of cranial nerves

  12. Class Reptilia • Reptiles have direct development (I.e. no larval stages) • are oviparous • Ovoviviparous • some are viviparous

  13. Class Reptilia • Reptiles like amphibians are poikilotherms, • but some do have a degree of control of body heat (i.e., lizard sunning self on rock)

  14. Classification of Reptiles

  15. Order Testudines (=Chelonia)turtles and tortoises • 330 species • body in case of dermal plates; • dorsal carapace and ventral plastron; • vertebrae and ribs fused to shell • jaws without teeth

  16. Order Squamatalizards and snakes • Suborder Sauria (lizards) • 3000 species • four limbs • moveable eyelids and eyeswith ear openings

  17. Order Squamatalizards and snakes cottonmouth • Suborder Serpentes (snakes) • 2700 species • limbs and ear openings absent • no eye lids; eyes can't move • Heat sensing pits in Pit vipers Black racer Milking diamondback

  18. Order Squamatalizards and snakes • Suborder Amphisbaenia (worm lizards) • 130 species • limb girdles vestigial • eyes hidden under skin

  19. Order Crocodilia • crocodiles and alligators • 25 species • four chambered heart • Oviparous; 20-50 eggs Crocodile; 4th tooth bottom jaw visible when mouth is closed, jaw narrow Alligator; 4th tooth bottom jaw not visible when mouth closed

  20. Order Sphenodonta =Rhynchocephalia • tuatara • Two living species • third eye (parietal) fairly well developed • no copulatory organs; primitive • Only found in New Zealand • Long lived up to 70 yrs • Live in burrows

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