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
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
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
All toads are frogs
but not all frogs are toads.
• Terrestrial & aquatic
• Most breathe through skin
– others w/ gills...
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- Fall '10
- limbs, w/ free-swimming adults