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Amphibians & Reptiles Donald Winslow, 7 April 2008 Readings from Hickman, et al., 2008 Ch 25 544-559 (amphibians)‏; Ch 26: 563-582 (reptiles)‏

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Presentation on theme: "Amphibians & Reptiles Donald Winslow, 7 April 2008 Readings from Hickman, et al., 2008 Ch 25 544-559 (amphibians)‏; Ch 26: 563-582 (reptiles)‏"— Presentation transcript:

1 Amphibians & Reptiles Donald Winslow, 7 April 2008 Readings from Hickman, et al., 2008 Ch (amphibians)‏; Ch 26: (reptiles)‏

2 Colonization of land by tetrapods Early tetrapods colonized land in Devonian Period, radiated during Carboniferous Double circulation, pulmonary & systemic circuits Fins became legs—humerus, radius, ulna Ichthyostega Coelacanth Lungfish Ichthyostega Amniota AnuraApodaCaudata

3 Class Amphibia Can use land, but usually tied to water for reproduction Webbed feet, forelimb usually with 4 digits Skin smooth & moist with many glands, chromatophores, no scales Respiration by skin, gills, and/or lungs, 3-chambered heart (2 atria)‏ Ectothermal, paired mesonephric kidneys, urea main nitrogenous waste Separate sexes, usually oviparous, mesolecithal eggs laid in water Metamorphosis Order Apoda (caecilians)‏ No legs, tropical forests, internal fertilization, egg-guarding Order Caudata or Urodela (salamanders)‏ Internal fertilization, female picks up spermatophore Aquatic species metamorphic, gills as larvae & lungs as adults Terrestrial species develop directly; plethontids breathe thru skin Paedomorphic species (mudpuppy, axolotl) retain gills as adults American newts: aquatic larvae, terrestrial efts, aquatic adults Parental care Order Anura (frogs & toads)‏

4 Vocalization External fertilization during amplexus Egg, tadpole stages, adult Family Ranidae Bullfrog, leopard frog, etc. Family Hylidae Treefrogs Family Bufonidae Toads

5 Factors affecting amphibian declines Droughts Wetland losses Pollutants Introduced predators & competitors Bullfrog, African clawed frog Ozone depletion Diseases—chytridiomycosis

6 Amniotes Enclosing the pond Anapsids Turtles secondarily anapsid Diapsids Lepidosaurs Snakes, lizards, amphisbaenas Tuataras Archosaurs Crocodilians, dinosaurs, birds Synapsids—Mammals

7 Class Reptilia (paraphyletic taxon)‏ Shelled, amniotic egg Extra-embryonic membranes Amnion, chorion, allantois Most species entirely terrestrial Dry, scaly skin, chromatophores Powerful jaws, ectothermic Internal fertilization, separate sexes Adaptations to conserve water Higher blood pressure than amphibians No gills, respiration usually by lungs Main nitrogenous waste is uric acid

8 Class Reptilia Order Testudines (turtles)‏ Superorder Lepidosauria Order Squamata Order Sphenodonta Superorder Archosauria Order Crocodilia


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