L05_Ancient_bony_fishesHO11

L05_Ancient_bony_fishesHO11 - EEMB 106 Lecture 5 Ancient...

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EEMB 106 – Lecture 5 – Ancient bony fishes 1 SuperClass Gnathostomata - Jawed fishes Class Placodermi (plate-skinned) extinct Class Chondrichthyes living Grade Teleostomi Class Acanthodii (spiny sharks) extinct Subgrade Eutelostomi, a.k.a. Osteichthyes, “bony fishes” Class Sarcopterygii living Class Actinopterygii living Euteleostomi or Osteichthyes • Appeared 425 mya during the Silurian • Probably evolved initially in freshwater • 380 mya ago bony fishes were dominant • Ostracoderms had just died out • Acanthodians, placoderms, elasmobranchs were still in existence • Devonian: ‘Age of fishes’ Characteristics of bony fishes A) jawed B) true bony skeleton, can be secondarily lost C) bony operculum covering gill arches D) 3 semicircular canals E) paired fins F) lungs, or swimbladders in advanced forms, or lost in benthic forms G) lepidotrichia replace ceratotrichia during ontogeny; bony supports for fins SuperClass Gnathostomata - Jawed fishes Class Sarcopterygii , lobed fins SubClass Coelacanthimorpha, coelacanths SubClass Dipnoi, lungfish “Tetrapodomorpha” including Osteolepidiformes, extinct - including Tiktaalik , the “missing link” - probably gave rise to tetrapods, thus humans Class Actinopterygii , ray fins SubClass Cladistia (bichirs) SubClass Chondrostei (sturgeons, paddlefish, etc.) SubClass Neopterygii (everything else) Class Sarcopterygii - lobed fins • appeared 400+ mya • marine and freshwater • lobed fins = series of bony elements link fins to pelvic and pectoral girdle (like tetrapods) • jaw suspension is autostylic • cosmine = complex tissue covers scales
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EEMB 106 – Lecture 5 – Ancient bony fishes 2 Class Sarcopterygii - lobed fins SubC. Coelacanthimorpha Coelacanth = hollow spine
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This note was uploaded on 01/10/2012 for the course EEMB 106 taught by Professor Staff during the Spring '08 term at UCSB.

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L05_Ancient_bony_fishesHO11 - EEMB 106 Lecture 5 Ancient...

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