ESS 345 Ichthyology - Juniata ESS 345 Ichthyology Evolutionary history of fishes 12 Feb 2019 (Who’s

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  • ESS 345 Ichthyology

    Evolutionary history of fishes

    12 Feb 2019 (Who’s birthday?)

    Quote of the Day: We must, however, acknowledge, as it seems to me, that man with all his

    noble qualities... still bears in his bodily frame the indelible stamp of his lowly origin._______,

    (1809-1882)

  • Evolution/radiation of fishes over time

    Era

    Cenozoic

    Fig 13.1

  • Fishes are the most primitive

    vertebrate and last common

    ancestor to all vertebrates

    They start the branch from all other

    living things with vertebrae and a

    cranium

  • Chordata

    Notochord

    Dorsal hollow nerve cord

    Pharyngeal gill slits

    Postanal tail

    Urochordata

    Cephalochordata

    Craniates (mostly Vertebrata)

  • Phylum Chordata sister is…

    Echinodermata

    Synapomorphy

    – They are deuterostomes

  • Fish Evolutionary Tree – evolutionary innovations in vertebrate history

    Craniata

    Vertebrata

    Gnathostomata Osteichthyes

    Actinopterygii (fish) Chondrichthyes

    Sarcopterygii

    Figure only from Berkeley.edu

    Handout

    For extant fishes

  • Hypothesis of fish (vert) origins

    Background

    570 MYA – first large radiation of

    multicellular life

    – Fossils of the Burgess Shale

    – Called the Cambrian explosion

  • Garstang Hypothesis

    1928

    Neoteny of sessile invertebrates

    Mistake that was “good”

    Mudpuppy

  • First Vertebrates

    Vertebrates appear shortly after Cambrian

    explosion, 530 MYA

    – Conodonts

    Notochord replaced by segmented or

    partially segmented vertebrate and brain is

    enclosed in cranium

  • Phylogenetic tree

    X

    Other “inverts” Echinoderms, et al.

    Vertebrate phyla

    DeuterostomesProtostomes

    Nephrozoa – bilateral animals

  • First fishes were jawless appearing in late

    Cambrian to Ordovician

    No fossils exist for extant jawless fishes

    (soft bodied)

  • Ostracoderms

    “Shell skinned”, appear 450-460 MYA

    First major vert radiation (extinct 350

    MYA)

    – No jaw, no paired fins, heavy bony armor

    – Marine and freshwater, small (

  • Placodermi

    “Plate skinned”, 380 MYA they are abundant

    Bony plates, got big

    Jaws, paired appendages, depressiform

    Die out 350 – 325 MYA, probably sister

    group Acanthodii

  • Acanthodii

    440 MYA thru Permian

    Appear before Placoderms and last longer,

    but less diverse/abundant

    First jawed fishes (allows great

    specialization); how jaws originated…

  • Acanthodii

    Many paired fins

    Fin fold theory

    3 pairs otoliths, bony opercula,

    branchiostegal rays

  • Early groups of fish – Modern

    Representatives

    Myxiniformes

    Chondrychthyes

    Osteichthyes

    Petromyzoniformes

    Gnathostomata

  • Chondrichthyes

    Poor fossil record, appear 415 MYA in

    marine deposits (Devonian)

    Cartilaginous skeleton

    Teeth not fused to jaw

    Unsegmented epidermal fin rays

    Oil filled liver

    Spiral valve intestine

    Claspers

  • Chondrichthyes (2 main lines)

    Elasmobranchii (sharks, rays, most diverse)

    – Batoidea (rays/skates) – deviates from many

    body plan (dorsoventrally flattened)

    – Selachii (sharks)

    – 5-7 gill openings, no swim bladder, largely

    predators

    Holocephali (chimaeras)

  • Early groups of fish – Modern

    Representatives

    Myxiniformes Chondrychthyes

    Osteichthyes

    Petromyzoniformes

    Gnathostomata

    Holocephali Elasmobranchs

  • Osteichthyes

    Lungs, bone, dermal bony scales,

    lepidotrichia (dermal)

    Physostomous

    Physoclistous

    FW mostly, stagnate tropical waters

  • Subclass Sarcopterygii

    Lobed fin fishes

    Lungfishes

    – Lungs, cartilaginous skeleton, spiral valve

    intestine

    – Internal nostrils connect to pharyngeal region

    – S. America, Africa, and Australia

    Coelacanth

    – External nostrils, large swim bladder

    Osteolepimorpha

  • Early groups of fish – Modern

    Representatives

    Lungfish

    Sarcopterygii

    Osteichthyes

    Coelacanth

    Osteolepimorpha

    Actinopterygii

  • Subclass Actinoptergyii

    Diverse and hard to generalize

    Devonian but minor until Carboniferous

    period 350 MYA when large tropical

    environments abounded and land masses

    were close to the equator

    Most dominant type of fish since

  • Early groups of fish – Modern

    Representatives

    Lungfish

    Sarcopterygii

    Osteichthyes

    Coelacanth

    Osteolepimorpha

    Actinopterygii

  • Subclass Actinoptergyii

    Scales become less complex, and bony

    – Ganoid scales

    Branchiostegal rays

    Swim bladder - hydrostatic organ

    Homocercal tail

    Fin rays become more spiny

    Fin placement: P1, P2

  • Early groups of fish – Modern

    Representatives

    Lungfish

    Sarcopterygii

    Osteichthyes

    Coelacanth

    Osteolepimorpha

    Actinopterygii

    Chondrostei

    Neopterygii

    TeleosteiGars Bowfins

  • Multicellular – 3 tissue layers