BIOL 202 Lecture Notes - Lecture 5: Lissamphibia, Sacrum, Barbourula
16 Mar 2016
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Lecture 5 amphibians (evoluion of girdles & limbs) Allow animals to lit limb up over the terrain. Also provides strong focal base against which to apply pressure and pivot. Sarcopterygian ish homologous ins with limbs of acanthostega and ichthyostega. Temnospondyl ancestors only labyrinthodonts to survive permian (paleozoic) era. Began to show transiional features of modern amphibians. Great dying = fossil gap no record of intermediates. Loss of ancient skull and girdle bones, simpler skeleton. Terrestrial and freshwater habitats (obligate to water in at least one stage of their life cycle) Don"t spread easily (not found on islands) Eggs very simple, only need to be deposited in water or very damp environment for success reproducion. Why are modern amphibians so much smaller than ancestors and tetrapods (evoluion at similar imes or later: surface area to volume raio (using skin as gas exchange organ means that certain constraints) Gas exchange: bornean lat-headed frog (barbourula kalimantanensis, first lungless frog discovered, uses cutaneous respiraion.
