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Unformatted text preview: OVERVIEW OF THE TETRAPODS A. Class LABYR INT HODONT IA- The original terrestrial vertebrates Possessed : Labyrinthodont teeth [Fig 13.12] Sarcopterygium; Lateral-line system Bony scales; Internal gills in some Ex: Acanthostega [Fig 3.23, p 103), Ichthyostega [Fig 3.24, p104) B. Class AMPH IB IA Subclass LISSAMPHIBIA--includes the modern forms which are: Small bodied; Respire through skin; Have pedicellate teeth; Possess an extra bone (the auricular operculum) associated with the ear. Life cycle involves bifaceted ontogeny (aquatic larva followed by adult that is generally terrestrial); Possess only 1 extraembryonic membrane (yolk sac) 1. Order URODELA (=CAUDATA )- the salamanders Material : Necturus, our primitive tetrapod Characters : Generally quadrupedal with long tail; Lack eardrums Lack the otic notch that holds the tympanum [Reprentative lissamphibians- Fig 3.25, p105] 2. Order SAL IENT IA (= ANURA )- frogs & toads Material...
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