Evolution of Fish :Evolution of Fish Armin Eskandari


Age of Animals :Age of Animals -Nearly 4 billion years that life has existed on Earth. Evolution produced little beyond bacteria, plankton, and multi-celled algae. But beginning about 600 million years ago in the Precambrian, the fossil record speaks of more rapid change. First, there was the rise and fall of mysterious creatures of the "Vendian biota" or "Ediacara fauna“. Vendian Period, 600-540MYACambrian Period, 540-500 MYA (new timescale)Ordovician Period, 500-425 MYASilurian Period, 425-408 MYADevonian Period, 408-362 MYACarboniferous Period, 362-290 MYAPermian Period, 290-245 MYATriassic Period, 245-208 MYAJurassic Period, 208-145 MYACretaceous Period, 145-65 MYATertiary Period, 65-1.64 MYAQuaternary Period, 1.64 MYA - present


Cambrian Period, 540-500 MYA (new timescale) :Cambrian Period, 540-500 MYA (new timescale) FA of exoskeletal material ,a laminated crust in arthropods. FA of many invertebrate phyla. (jawless fish, ostracoderm also known as Agnatha). Just like the molluscs and arthropods, the early fish had a armor. They had ate by sucking in mud through their mouths. They filtered out particles of food as the water left through their gills. Some jawless fish still survive today. (lampreys & hagfish).


Origin of Fishes :Origin of Fishes Fish evolved from primitive Chordates Phylum Chordata Characteristics: 1-Dorsal, hollow nerve chord 2-Notochord: 2-1-Flexible dorsal rod support 2-1-Present at some stage in all chordates(usully in emberyonic development) 2-1-Present in adults of many fishes(Shark, Rays,Sturgeons) 3-Pharyngeal gill slits (p in emberyos of all Vertebraes)


How did Fish evolved? :How did Fish evolved? Cephalochordata (Lancelets) Tunicate


Earliest Accepted Chordate :Earliest Accepted Chordate Pikaia, Burgess Shale The history of the vertebrates may begin with Pikaia, a pre-vertebrate with a notochord, which places it in Phylum Chordata. See the notochord near the dorsal surface. The rib-like features are muscles. Middle Cambrian


When did fish first Evolved? :When did fish first Evolved?


Where did Fish Evolved? :Where did Fish Evolved? Generally belived to be in OCEAN because: 1-Habitat of other Chordates 2-Marine deposits contain most early Vertebrate Fossils


Major groups of jawless fishes :Major groups of jawless fishes Ostracoderms (extinct) Agnathans Hagfishes (class Cephalaspidomorphi) Lamprey (class Myxini)


Evolutionary relationships of vertebrates :Evolutionary relationships of vertebrates


Evolution of Fish :Evolution of Fish


Evolution of Fishes :Evolution of Fishes


Geologic Ranges of Major Fish Groups :Geologic Ranges of Major Fish Groups


Age of Fish :Age of Fish Many fish evolved during the Devonian Period including the abundant acanthodians placoderms ostracoderms other fish groups


Evolutionary relationships :Evolutionary relationships Poor Fossil record Subject of much debite extinct groups:Conodonts(<2mm)(510M year-210 My) Ostrachoderms(460My) Abundent and Diverse, No Jaws and Paired Fins, Had Bony Armor


Ostracoderms :Ostracoderms A. Pteraspis was about eight inches long. B. Hemicytaspis was about 5 inches long


Myxiniformes:Hagfishes :Myxiniformes:Hagfishes jawless fishes,Not vertebrate,Lack bone and vertebrae, 40 Species, No fins or accessoies,Tendacles around mouth part


Gnathostomata :Gnathostomata Gnathostomata(Jawed Vertebrates) Osteichthyes (Bony fishes) Chndrichthyes (Cartilaginus fishes) Placoderms


Placoderms :Placoderms Earliest Jawed fish440-350 My ego.(extinct)Armored,internal skeleton,paired fins,No affinity for modern fishes Skull of Dunkleosteus, a Late Devonian placoderm. The skull is more than three feet long. Dunkleosteus, twenty-three feet long, pursuing a six-foot shark Cladoselache


Diverse Placoderms :Diverse Placoderms


Acanthodians :Acanthodians Climatius, an acanthodian about three


Acanthodians :Acanthodians The fossil remains of the first jawed fish are found in Lower Silurian rocks and belong to the acanthodians, characterized by: large spines scales covering much of the body jaws teeth and reduced body armor


Holocephalii(chimeridae, ratfishes) :Holocephalii(chimeridae, ratfishes) 30 Species,bottom dwelling,present since 400My


Osteichthyes(Bony fishes) :Osteichthyes(Bony fishes) Osteichthyes(Bony fishes) Sarcopterygii(Lobe-finned fishes) Acthinopteriygii(Ray-finned fishes) Coelacanthiformes( (Coelacanths) Dipnoi(Lung fishes) bone,bony scales,Evolved in fresh water


Slide 33:Bony Fishes Cheirolepsis, a primitive ray-finned fish of mid-Devonian age, about 22 inches long. Eusthenopteron, an Upper Devonian lobe-finned fish, about 20 inches long.


Coelacanths :Coelacanths piscivore :a carnivorous animal which lives on eating fish.


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Actinopteygii(Ray finned fishes) :Actinopteygii(Ray finned fishes) Actinopteygii Neopterygii(other modern bony fishes) Chondrostei(Sturgeons and paddlefishes)


Neopterygii (modern Bony fishes) :Neopterygii (modern Bony fishes)


Gnathostomes :Gnathostomes


... Gnathostomes :... Gnathostomes


Jaw fishes :Jaw fishes


Slide 71:Male


Teleost Evolution :Teleost Evolution


Origin of Jaws :Origin of Jaws Primitive configuration of fish jaws and jaw supports shown in Carboniferous shark fossil.


The Origin of Jaws :The Origin of Jaws Jaws developed from gill arches A second set of arches formed support for the jaws Same nerves and bloodvessels feed lamprey gillarches and shark jaws Jaws gave fish an enormous advantage and let to a huge adaptive radiation in Devonian


Evolution of Jaws :Evolution of Jaws


Cartilaginous Fish :Class Chrondrichthyes, represented today by sharks, rays, and skates, first evolved during the Middle Devonian -they are important members of the marine vertebrate fauna Cartilaginous Fish


Bony Fish :Because bony fish are the most varied and numerous of all the fishes and because the amphibians evolved from them, their evolutionary history is particularly important There are two groups of bony fish the common ray-finned fish and the less familiar lobe-fined fish Bony Fish


Ray-Finned and Lobe-Finned Fish :Arrangement of fin bones for (a) a ray-finned fish (b) a lobe-finned fish muscles extend into the fin allowing greater flexibility Ray-Finned and Lobe-Finned Fish


Ray-Finned Fish Rapidly Diversified :From a modest freshwater beginning during the Devonian, ray-finned fish, which include most of the familiar fish such as trout, bass, perch, salmon, and tuna rapidly diversified to dominate the Mesozoic and Cenozoic Seas Ray-Finned Fish Rapidly Diversified


Amphibians Evolved from Crossopterygians :The crossopterygians are an important group of lobe-finned fish because amphibians evolved from them During the Devonian, two separate branches of crossopterygians evolved one led to the amphibians while the other invaded the sea Amphibians Evolved from Crossopterygians


Coelacanths :The crossopterygians that invaded the sea called the coelacanths were thought to have become extinct at the end of the Cretaceous In 1938, however, a fisherman caught a coelacanth off Madagascar since then several dozen more have been caught both there and in Indonesia Coelacanths


Slide 83:Diverse in shape and size during the Devonian Fin structure most resembles tetrapod limbs


The crossopterygians that became amphibians were the Rhipidistians. :Eusthenopteron, a member of the rhipidistian crossopterygians had an elongate body and paired fins that it could use to move about on land The crossopterygians are thought to be amphibian ancestors The crossopterygians that became amphibians were the Rhipidistians.


Fish/Amphibian Comparison :Similarities between the crossopterygian lobe-finned fish and the labyrinthodont amphibians Fish/Amphibian Comparison Their skeletons were similar


Transition from Water to Land :In passing from water to land, plants and animals had to solve the same basic problem the method of reproduction was the major barrier to expansion into the various environments required evolution of the seed in plants and the amniote egg in animals Transition from Water to Land