The parade of the Craniates

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The parade of the Craniates

• Part 1

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Major synapomorphies of the Craniates

• Developmental
• Neural crest
• Neurogenic placodes
• Nervous System
• Above
• Braincase (skeletal)
• Complex sense organs
• Cranial nerves
• Tripartite brain

• Endocrine system is complex
• Gut
• Muscularization
• Regionalization
• Differentiated organs
• Cardiovascular
• Gills
• Heart
• Hemoglobin

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Craniate phylogeny and diversity of living species
Fig. 3.1
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Agnathans

• Jawless
• Include
• Ostracoderms
• Hagfishes and lampreys

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Ostracoderms

• Extinct
• Armored bony dermis
• Middle Ordovician (maybe Cambrian)
• Most lacked paired fins
• Length 2-3cm to 2-2.5m
• Heterocercal tail

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• Ostracoderms

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Hagfish and Lampreys

• Hagfish
• Marine
• Scavengers
• Lamprey
• Anadromous
• Buccal funnel
• Parasitic
• Historically conservative
• anatomy (Carboniferous)

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Gnathostomes
Ostracoderms

• Paleozoic
• Placoderms
• Chondrichthyans
• Teleostomes
• Acanthoidians
• Ostichthyans

jaws
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Placoderms

• Devonian (400mya)
• Paired p. and p. fins
• Jointed, bony shields

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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

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Squaliformes - sharks

• Lateral gill slits

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Rajiformes skates, rays, sawfishes

• Ventral gill slits

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Holocephalans

• Upper jaw connected to braincase

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Acanthodians and Osteichthyans

• Acanthodians
• Extinct
• Hollow spines in paired fins
• Bony armor

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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

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Basal Actinopterygians
Neopterygii
Ganoid scale
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Neopterygians
Teleosts (23,000 species)
Bowfin
Gar
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Sarcopterygians
Tetrapods
Lungfishes (Rhipidistians)
Coelocanths (Actinistians)
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The parade of the craniates

• Part 2

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Tetrapoda