From Amphibians to Reptiles

From Amphibians to Reptiles Porsha Chillis and Cameron Volpe Amphibians begin Evolved from Sarcopterygii-rhipistidians Late Devonian (about 400 mya) Early amphibians Acanthostega

Ichthyostega Characteristics of Amphibians Cold-blooded Moist skin-absorbs oxygen and water Fertilization and development of eggs in water Tied to the water

Orders of amphibians Anura Frogs Toads Urodela Newts Salamanders

Gymnophionia Caecilians Naked snake Anura Urodela

Gymnophionia Amphibians start to evolve Developed lungs and scales Stronger legs Shelled egg Oldest fossilized egg-280 mya Shell prevented drying out

Seymouria Class-Labyrinthodont Carboniferous period Westlothiana lizziae 350 mya Lepidosauria

Lizard Tuatara Snake Testudines Crocodylia Reptiles become more abundant

Hylonomus lizziae (350 mya) Oceans receded Plants well established Insects abundant Reptilian advantage Independent from water Internal fertilization Laid eggs on land

Thick impermeable skin Stronger limbs Return to water 80 million years after reptiles evolved Earliest marine reptiles-Mesosaurus Webbed feet, paddle-like tail Became marine dinosaurs

Return to land to lay eggs Turtles arose Late Triassic (220 mya) Anapsids Snake evolution Came from a group of lizards Lost legs and external ears Developed a clear eye covering

Developed distinctive way of moving Hox gene evolution Study on the limbs of tetrapods Virginia Abdala and Rui Diogo Dissections of the pectoral and forelimb muscles General skeletal pattern of amphibians and

reptiles was acquired early in evolutionary history Highly conserved characters Many homologies Confirmed reptilian musculature stronger than amphibian Works Cited Abdala, Virgina, and Rui Diogo. "Comparative Anatomy, Homologies and Evolution of the Pectoral and Forelimb

Musculature of Tetrapods with Special Attention to Extant Limbed Amphibians and Reptiles." Journal of Anatomy (2010): 536-73. "Amphibians." UXL Encyclopedia of Science. 2002. Encyclopedia.com. 26 Feb. 2011

. Jothi. "Changeover from Amphibians to Reptiles." LexisNexis Academic. LexisNexis, 27 Dec. 1996. Web. 29 Jan. 2011. Futuyma, Douglas J. Chapter 4: Evolution in the Fossil Record Evolution. Sunderland, MA: Sinauer Associates, 2009. 80. "Hylonomus." Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc., 2011. Web. 2 Mar. 2011. . Origin of snakes makes a long story. The Press (2000): 19. Lexis Nexis. Web. 29 Jan. 2011. Pough, F. Harvey. Herpetology. Upper Saddle River, NJ: Prentice Hall, 1998. Print.

"Reptile and Amphibian Evolution." Scared Cricket. Michelle Caldwell. Web. 02 Mar. 2011. . "Reptile Evolution: Humble Beginnings." Reptiles: Great As Pets Or In The Wild. 16 Nov. 2010. Web. 03 Mar. 2011. . Sheen, Judy P.. "Reptilia." Animal Sciences. 2002. Encyclopedia.com. 26 Feb. 2011 . Short, Kevin, and Yomiuri. "Reptiles and Their Wriggling Relatives." LexisNexis Academic. LexisNexis, 2 Nov. 1999. Web. 29 Jan. 2011. "Snake." Wikipedia, The Free Encyclopedia. Wikimedia Foundation Inc., 28 Feb. 2011. Web. 03 Mar. 2011.

en.wikipedia.org/wiki/Snake>. "Weslothiana." Wikipedia: The Free Encyclopedia. Wikimedia Foundation, 21 Feb. 2011. Web. 2 Mar. 2011. . Questions?