The parade of the Craniates

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					The parade of the Craniates

           Part 1
      Major synapomorphies of the
               Craniates
1. Developmental              3. Endocrine system is
  •    Neural crest              complex
  •    Neurogenic             4. Gut
       placodes                 •   Muscularization
2. Nervous System               •   Regionalization
  •    Above                    •   Differentiated organs
  •    Braincase (skeletal)   5. Cardiovascular
  •    Complex sense            •   Gills
       organs
                                •   Heart
  •    Cranial nerves
                                •   Hemoglobin
  •    Tripartite brain
Craniate phylogeny
and diversity of
living species




   Fig. 3.1
               Agnathans
• Jawless
• Include:
  – Ostracoderms
  – Hagfishes and lampreys
             Ostracoderms
•   Extinct
•   “Armored” – bony dermis
•   Middle Ordovician (maybe Cambrian)
•   Most lacked paired fins
•   Length 2-3cm to 2-2.5m
•   Heterocercal tail
• Ostracoderms
Hagfish and Lampreys
• Hagfish
  – Marine
  – Scavengers
• Lamprey
  – Anadromous
  – Buccal funnel
  – Parasitic
  – Historically conservative
  anatomy (Carboniferous)
Gnathostomes




                        Ostracoderms
• Paleozoic
  – Placoderms
  – Chondrichthyans   jaws
  – Teleostomes
    • Acanthoidians
    • Ostichthyans
  Placoderms
• Devonian (~400mya)
• Paired p. and p. fins
• Jointed, bony shields
  Chondrichthyes
• Cartilaginous skeleton
• Bones in scales and teeth

  – Elasmobranchs (sharks, skates, rays,
  sawfishes)
     • Naked gill slits (cf. bony fish operculum)
     • spiracle
     • Heterocercal tail morphology
  – Holocephalans (Chimaeras (ratfish))
     •   Scales reduced to absent
     •   Upper jaw continuous with braincase
     •   Fleshy operculum
     •   Bony plates instead of teeth
Squaliformes - sharks
• Lateral gill slits
       Rajiformes – skates, rays,
               sawfishes
• Ventral gill slits
           Holocephalans
• Upper jaw connected to braincase
 Acanthodians and Osteichthyans
• Acanthodians
  – Extinct
  – Hollow spines in paired fins
  – Bony armor
                Osteichthyans
• The extant bony fish
  – Bony skeleton
  – Airsac
  – Paired appendages (fins)

  – Actinopterygii – ray-finned fishes
     • Basal actinopterygians (sturgeons, paddlefishes, Polypterus)
     • Neopterygians (gars, bowfins, teleost fishes)

  – Sarcopterygii – lobe-finned fishes
     • Actinistians – coelacanths
     • Rhipidistians – lungfishes
Basal Actinopterygians




                   Ganoid scale
Neopterygians
                               Teleosts (23,000 species)



                      Bowfin




                Gar
Sarcopterygians



                                        Tetrapods


           Lungfishes (Rhipidistians)


      Coelocanths (Actinistians)
The parade of the craniates

           Part 2
Tetrapoda

				
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posted:5/27/2013
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