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Skeleton, Skin and Scales. evolutionary time. High # bones. Low # bones. Skull. Evolutionary tendency. Fusion of skull bones. Neurocranium (brain case) Branchiocranium (endoskeletal arches, original gill arch supports). Chondrocranium (original cartilagenous braincase)

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Presentation Transcript
skull

evolutionary time

High #

bones

Low #

bones

Skull

Evolutionary tendency

Fusion of skull bones

skull1
Neurocranium(brain case)

Branchiocranium (endoskeletal arches, original gill arch supports)

Chondrocranium(original cartilagenous braincase)

Dermatocranium (dermal bones attached to skull)

Arches:

Mandibular

Palatine

Hyoid

Opercular

Branchial

Skull
branchiocranium
Branchiocranium
  • Mandibular Arch (cartil. & dermal origin)
    • Sharks
      • Palatoquadrate Cartilage (top jaw)
      • Meckel´s Cartilage (bottom jaw)
    • Bony Fishes
      • Premaxillae, Maxillae, Supramaxillae (top jaw)
      • Dentary, Angular (bottom jaw)
  • Palatine Arch (cartil. origin)
branchiocranium1
Branchiocranium
  • Hyoid Arch or Supensorium (cartil. Orig.)
    • Provides support and attachment to skull.
      • lower jaw (Quadrate)
      • opercular apparatus
  • Opercular Arch (dermal origin)
    • Protects gills (Opercule)
branchiocranium2
Branchiocranium
  • Branchial Arches (cartil. origin)
    • Support gills (Ceratobranchial & Epibranchial)
    • Help chewing (Pharingeal bones)
protrusible mouth ascending process on premaxilla that slides along front of skull
Protrusible mouth (ascending process on premaxilla that slides along front of skull).

premaxilla

maxilla

mandible

vertebral column
Vertebral Column

Precaudal

Caudal

slide18
Fins
  • Pectoral Girdle
    • Not attached to vertebral column
    • Attached to Skull
  • Pelvic Girdle
    • Not attached to vertebral column
  • Caudal Fin
    • Protocercal, heterocercal, homocercal
slide19
Fins
  • Median Fins
    • Sharks
      • Ceratotrichia (dermal)
      • Radials (cartil.)
slide20
Fins
  • Median Fins
    • Bony Fishes
      • Ceratotrichia

(in larval stages)

      • Lepidotrichia (dermal)
      • Pterygiophores (cartil.)
soft rays true spines
Soft rays True Spines

soft

segmented

branched

bilateral

hard and pointed

unsegmented

unbranched

solid

scale types
Scale Types
  • Placoid
    • Sharks, rays and chimaeras
    • dermal and epidermal origin
    • Irrigated pulp cavity + dentine + vitrodentine
    • homologous to vertebrate teeth
  • Cosmoid
    • Lungfishes
    • originated by fusion of placoid scales
    • Two bone layers + cosmine + vitrodentine
scales
Scales
  • Ganoid
    • Sturgeons, paddlefish and gars
    • modified cosmoid scale
    • Two bone layers + dentine + ganoine
  • Cycloid and Ctenoid
    • Bony fishes
    • evolved from ganoid scale (loss of ganoine)
    • Almost all dermal
    • Overlapping (shingle-like)
slide26

PLACOID

COSMOID

GANOID

slide27

CYCLOID

CTENOID

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