Scientific articles for Friday oral reports: • Must be from peer-reviewed journal, not website • Must get access to entire article, not just abstract as • EITHER A) hard copy, B) HTML download, or C) PDF
Based on the graph, explain how catch continues to increase through time • while per capita catch does not • What is “bycatch”? • What are the ecological effects of overfishing? • Where does the coelocanth occur? • Can you drown an Australian lungfish by holding its head under water? • 5. What evolutionary events had already occurred by the Devonian • that were critical for the evolution of the tetrapods?
Major evolutionary events in Vertebrate History • Evolution of jaws and paired appendages 2) The Evolution of Tetrapods and Invasion of Terrestrial Environments
Devonian Age of Fishes- Ostracoderms, placoderms, acanthodians, chondrichthyes, actinopterygians, sarcopterygians, first tetrapods!!
Devonian conditions Warm shallow seas Land with primitive plants Land with terrestrial invertebrates Why important?
Lots of aquatic Devonian predators and competitors So what? Hypotheses about evolutionary forces driving invasion of the land include:
Osteolepiforms+ Amphibians Amniotes Lungfish Acanthostega+ Coelocanths Ichthyostega+ P* * Panderichthyes See Figure 9-2 Important fossil forms in the evolution of vertebrates Osteolepiforms & Panderichthyes = sarcopterygian fish Acanthostega & Ichthyostega = “stem tetrapods”
Osteolepiform Panderichthyes Fig 9-3
Evolution of Tetrapods – wonderful example of transitional forms Osteolepiform fish Acanthostega Ichthyostega
Osteolepiform Acanthostega Ichthyostega Fig 9-3 & 9-7
Challenges of Terrestrial Life: Respiration via lungs Obtaining food Support
Feeding on Land Catching and swallowing prey Suction feeding
Moving onto land – “I’m so heavy!” Fig 8-3 Vertebrae, limbs, girdles
Attaching limb girdles To vertebral column Muscular attachment Of flat girdle Bony attachment via sacrum and ilium of pelvis
Evolution of the tetrapod limb - Trying to Find Fingers in Fins Fig 9-5 Osteolepiform Dipnoan “pinky” thumb Only tetrapods
Note major shifts in Tetrapods Fig 8-4