Lecture_24 Mammals

Lecture_24 Mammals - Gel 107 Lecture #24: MAMMALS November...

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Gel 107 Lecture #24: MAMMALS November 26, 2008 1) What are mammals and when did they appear? a) Three living groups of mammals (mammalian) i) Monotremata, marsupialia, and Placentalia b) Mammaliaformes: contains non-living groups c) Monotremes: i) Smallest group ii) Only survive in Australia iii) Ex. Duckbilled platypus and ekedna iv) Almost extinct v) Mammals that lay eggs rather than giving birth to babies. Considered mammals because offspring suckle after hatching d) Marsupials: i) Pouched animals ii) Have no placenta, so babies are tiny. e) Placentals i) Biggest and most diverse group ii) Give birth to large babies iii) Have placenta f) All the living groups emerged during the early Cenozoic i) However, we do have fossils from cretaceous g) Eutheria : oldest placenta group lineage h) Appeared during : LATE TRIASSIC i) Early Jurassic, “Mammaliaform” (1) Looked like mammals (2) Oldest fossil during late Triassic 2) What are the four major stages of synapsid evolution, and “mammal-like” reptiles? a)
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This note was uploaded on 03/15/2010 for the course GEL GEL 107 taught by Professor Jishin during the Winter '09 term at UC Davis.

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Lecture_24 Mammals - Gel 107 Lecture #24: MAMMALS November...

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