osteichthyes - >27,000 bony fishes, 13,000 herps, 9000 birds, 4800 mammals
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Two major branchesOf Osteichthyes1. Sarcopterygia
Lung fish Fig 6-3Coelocanths Fig 6-4Tetrapods
2 ActinopterygiaRay-finned fishes
Trends in Actinopterygian Evolution Fig 6-2, 6-8
1) Heavy body armor light overlapping scales Ganoid scales cycloid, ctenoid
Ctenoid
1. Are mammals on this cladogram? If so where?
2. What is the major difference between ostracoderms and placoderms?
3. For actinopterygians, what is the ancestral condition in terms of scale type and tail type?
4. Sharks maintain neutral buoyancy without a swim bladder. How?
5. What would you predict about the organs for maintaining neutral buoyancy in bottom-dwelling rays and actinopterygians?
6. If a physoclistous fish were swimming to deeper depths, what would the ovale of the swim bladder be doing?
4) Evolution of protrusible jaws and pharyngeal jaws
Scissors = gar
Maxilla rotates out – trout
Premaxilla slides outProtrusible tube
Advantage??
Reproduction – most actinopterygians oviparous
Marine- planktonic Freshwater & nest–guarding Marine - demersal
Swimming and Actinopterygian fish
“The gap between the swimming fish and the scientist is closing, but the fish is still well ahead”Lindsey 1978
S. America
Africa
Australia Aestivating African lungfish
Marjorie Courtney-LatimerWith the mounted S Africa specimenOops! No internal organs or skeleton!
1938
Sketch sent to JLB Smith
JLB Smith and flight crewwith 2nd coelocanth
Smith sleeps with his prize
“I need a government plane!”