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Home , Fish anatomy, Haikouella, Jenny Clack, Osteichthyes, Swim bladder

Fish and

Geology 331 Phylum Chordata: Subphyla Urochordata, Cephalochordata, and: Subphylum Vertebrata : jawless , includes the , , lampreys, and ostracoderms (armored jawless fish) Gnathostomes: jawed fish (an , not a taxon) Class Placoderms: armored fish Class : cartilaginous fish Class : bony fish Subclass Actinopterygians: ray-finned fish Subclass Sarcopterygians: lobe-finned fish Order Dipnoans: fish Order Crossopterygians: coelocanths and rhipidistians Class Amphibia

Fish- phylogeny Prothero, 2007 Urochordates: Sea Squirts. Adults have a pharynx with slits. Larval forms are free-swimming and have a . are thought to have evolved from the larval form by precocious sexual maturation. or Sea Squirts

mobile larva

sessile adult evolution Prothero, 2007 : Branchiostoma, the , a cephalochordate from the , a cephalochordate from the Lower of China A toothless, jawless hagfish , , Lower Cambrian of China - Chengjiang fauna, scale is 5 mm A living jawless fish, the , Class Agnatha Jawless fish do have teeth!

A fossil jawless fish, Class Agnatha, Ostracoderm, Hemicyclaspis, Agnathan, Ostracoderm, Athenaegis, Silurian of Canada Agnathan, Ostracoderm, Pteraspis, of the U.K. Agnathan, Ostracoderm, Liliaspis, Devonian of Russia Jaws evolved by modification of the gill arch .

The placoderms were the armored fish of the . Grew up to 10 m in length. Placoderm, Dunkleosteus, Devonian of Ohio Asterolepis, Placoderms, Devonian of Latvia Placoderm, Devonian of Australia Chondrichthyes, Great White Fossil teeth of a , Megalodon Himantura - a ray Fish : Ray-finned fish Osteichthyes: ray-finned fish: clownfish Osteichthyes: ray-finned fish, deep water species Lophius, an Eocene fish showing the ray fins. This is an . Osteichthyes, ray-finned fish, , ray-finned, Jurassic of Australia Osteichthyes, ray-finned fish, Eocene, Wyoming : Lobe-finned fish structure in fins of ray-finned and lobe-finned fish Comparison of Ray Fins and Lobe Fins Osteichthyes, lobe-finned fish, Devonian of Scotland Coelocanth, a living lobe- finned fish: Osteichthyes, Sarcopterygian of the coelocanth A Coelocanth Evolution of the tetrapod walking leg from the lobe fin Sauripterus, rhipidistian, Late Devonian, Pennsylvania Evolution of tetrapod legs from lobe fins, late Devonian to early Mississippian Evolution of Tetrapods

Prothero, 2007 Late Devonian fin with fingers from a lobe- finned fish, Pennsylvania

Tiktaalik rosea from the Late Devonian of Ellsmere Island, Canada, 2006 rosea from the Late Devonian of Ellsmere Island, Canada, 2006 Tiktaalik rosea on Colbert Report

Tetrapods: Acanthostega and , Devonian of Greenland. Fish or Tetrapods? roof of the Late Devonian tetrapod Ichthyostega Acanthostega using its legs to lift its head out of the stagnant water to breathe Hindlimb of Ichthyostega, Devonian of Greenland Fish with Fingers, Ichthyostega: Photographs of part and counterpart superimposed to show seven digits

South American in its burrow. The lung evolved in early Devonian bony fish and became the of ray-finned fish. An Australian lungfish with well developed lobe fins , ray-finned fish acting like . They gulp air into their swim bladder. A Frog Fish, a modern ray-finned fish with “fingers” The evolutionary step from fish to was not difficult. Old Theory: evolved while looking for water in the Devonian when streams dried up during drought. New Theory: Lungs evolved for rapid swimming in the open . Later became the float bladder in most fish. amphibian, Seymouria, with 5 digits Summary of the Mid Paleozoic terrestrial invasion Guiness “Evolution” Video

If Jurassic Park Were In Different Geological Eras