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Ch 34 - Vertebrates (1 slide per page)-1

lungfishes tetrapods rod shaped bones surrounded by

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Unformatted text preview: ishes) • Operculum pumps to move water in mouth and out across gills • analogous to diaphragm of mammals • Swim bladder allows buoyancy - evolved from primitive lungs 48 Lobe-fins (Sarcopterygii) coelacanths + lungfishes + tetrapods • Rod shaped bones surrounded by a thick layer of muscle Limbs w/ digits Figure 34.2 (Campbell et al) 49 Lobe-fins (Sarcopterygii) Pectoral and pelvic fins (or limbs) joined to body by a single bone Lungfish vs. multiple bones in Chondrichthyes and Osteichthyes Shark Ray-finned fish 51 Lobe-finned fishes Actinistia: Coelacanths Marine Thought extinct for 60my Discovered in 1938 in South Africa by Marjorie Courtney Latimer Limbs w/ digits 52 Dipnoi: Lungfish • Have true lungs! (which develop into a swim bladder in ray-finned fish) • Also have gills • Survive seasonal desiccation by aestivating in mud Limbs w/ digits 54 Tetrapods Amphibians + Amniotes Limbs w/ digits Figure 34.2 (Campbell et al) 55 Lungfishes to Tetrapods • Clear fossil transition series – Series of lineages (all extinct) showing intermediate stages between lungfish (aquatic) and tetrapods (terrestrial) and amniotes. • Only amphibians & amniote lineages survived. Figure 34.21 (Campbell et al) Intermediates First Tetrapod Limbs w/ digits 56 Tiktaalik – a “fishapod” Discovered in 2006 Figure 34.20 (Campbell et al) 57 Lobe-finned fish to Tetrapods Lobe-finned fish 58 The transition to land: How? - Limbs evolve for moving in shallow water, and onto land for short periods. First tetrapods were amphibious. Still required water for laying eggs. Why? - Lungs evolved first and maintained for life in anoxic swamps - Legs evolve to exploit food on land (insects) 59 The modern amphibia Limbs w/ digits Figures 34.2 and 34.21 (Campbell et al) 60 Class Amphibia Frogs • • • • Salamanders Terrestrial, aquatic and arboreal Adults w/o tail External fertilization All toads are frogs but not all frogs are toads. • Terrestrial & aquatic • Most breathe through skin – others w/ gills...
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