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Monahan8 - Reptiles, Amphibians, Birds Introduction: 1....

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Reptiles, Amphibians, Birds Introduction: 1. Arms race between predator and prey - Cheetah is 7mph faster than its prey - Prey can usually last longer than its cheetah Continuation of Lecture: - Finishing the Tetrapods - Introducing to Reptilians, Amphibians, and Birds - Examining morphological jumps Reptilians Fig. 34-22 - Fish-like tail - Sophisticated limp development Fig 34-20 - Know the timing between Amphibians and Amniotes (370 mya) Amniotes (short-answer question about characteristics of terrestrially adapted life) i. Amniotic egg consisting set of extraembryonic membranes o Amnion o Chorion o Yolk Sac o Allantois ii. Fig 34-25 : Know everything in this diagram! Important principles of protection of young. a. Note the cephalization, the backbone, etc. b. Amnion: contains amniotic fluid surrounding embryo that protects embryo from getting bumped around c. Yolk: Provides nutrients to embryo independent of mother d. Allantois: Removes waste from embryo e. Everything contained in the chorion f. Shell: Mineralization step (one step from mineralized teeth) g. Egg white is Albumen: serves as a buffering to keep embryo safe h. Video amphibian/ reptile/ bird development: iii. Other terrestrial adaptations include: relatively impermeable skin and ventilation of lungs by the rib cage Key adaptations to terrestrially adapted life: - Amniotic egg allows embryo to develop on land in its own private “pond”, reducing the dependence of tetrapods on an aqueous environment for reproduction - Rib cage to ventilate lungs instead of throat-based ventilation; allows for development of less permeable skin and the consequent conservation of water Reptiles: - Ectothermic: absorb external heat as the main source of body heat - (Humans: Endothermic: keeps body warm through metabolism) - Molecular causes for ectothermic vs. endothermic o Food + O2 CO2 + H2O + ATP + heat o Doesn’t need new biochemistry to be endothermic
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o We just need to trap the heat either by feathers or hair or a warm coat Dinosaurs: Oldest reptiles was 310 mya - Agile, fast-moving dinosaurs were probably endothermic (instead of ectothermic) - Also evidence of parental care among dinosaurs - Extinct at end of Cretaceous - Extinction caused by asteroid impact which sends up particles which blocks out the sun = collapse of vegetation First emergence of mammals: during Triassic Period 200 mya - Extinction of dinosaurs allowed diversification of small mammals already existing before - Diversification of mammals during Cenozoic Period - Emergence of mammals begin with Birds Origin birds: 10,000 species - descended from small, carnivorous dinosaurs - Archaeopteryx remains the oldest bird known - Flight requires energy, acute vision , fine muscle control (important to neuroscience studies) - Birds are big step from ectothermic to endothermic. -
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This note was uploaded on 01/27/2011 for the course BISC 120 taught by Professor Webb,wetzer,? during the Fall '07 term at USC.

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Monahan8 - Reptiles, Amphibians, Birds Introduction: 1....

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