Paleozoic Tetrapod Origins/Radiation
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Transcript of Paleozoic Tetrapod Origins/Radiation
Paleozoic Tetrapod Origins/Radiation
rhipidistian crossopterygian ancestry
• mid-late Devonian (360-370 mya)
• major structural changes:• limbs/girdles- better support & muscle
attachments• skull/jaws- new feeding modes• vertebrae- better support• lungs
hierarchical classification of the tetrapod vertebrates
• Tetrapoda (vertebrates with four limbs)• Amphibia• Lissamphibia (modern amphibians)
•Gymnophiona
•Caudata (salamanders)- Jurassic ~ 140 mya
•Anura (frogs & toads)- Triassic ~ 200 mya
Modern Amphibians: Lissamphibia
• general features:
• 'amphibious' life cycle (metamorphosis)• smooth, glandular skin• three chambered heart• carnivorous
Order Anura• distribution cosmopolitan except Antarctica;
tropics especially
• elongate hind limbs & powerful leg muscles
• strong pelvis fused to the vertebral column; posterior vertebrae fused into a urostyle
• feeding: sticky, protrusible tongue
• reproduction:•species specific vocalizations•external fertilization; amplexus
Anuran Anatomy
“protrusible tongue”
Order Caudata• distribution: primarily northern hemisphere
• paedogenesis- larvae becomes sexually mature
• courtship: species specific displays (visual, tactile, & chemical cues)
• internal fertilization; spermatophore transfer
• eggs laid in water or moist soil; larvae; aquatic & gilled in many
Salamander Anatomy
A few Oklahoma Amphibians
Amphibians of SE Oklahoma