Chondricthyes - Cartilaginous Fish

Paleozoic Radiation
1. Amphystylic jaw support
  1. Chondrocranium fixed to palatoquadrate
2. Body supported - Notochord + neural arches and cartilage
  1. Paired fins - fixed (no rotation)
3. Limited scales
4. 3 cusped teeth
  1. Tooth whorl - lots of new teeth developing, rotation to the front then falling out
    1. present in all extant sharks
Mesozoic Radiation
1. Hybodonts
2. Heterodont dentition - posterior teeth
  1. In batteries - several teeth whorl
3. Pectoral fins rotate - not fixed
4. Ceratotrichia
  1. Proteinaceous flexible fin rays
    1. Curve base to tip and front to back
  2. Produce lift and stability - greater thrust and counteract sinking
5. Amphistylic jaw support
  1. Terminal mouth
Extant radiation - sharks skate and rays (elasmobranchs)
1. Solid, calcified vertebrae
2. thicker, complex enamel teeth
3. Ventral mouth - overhanging rostrum
4. From Triassic and earlier. Jurassic and cretaceous genera still here
5. ~815 spp - all marine
6. Cartilaginous skeleton
7. Tails
  1. Heterocercal - vertabrae extend into lobe
  2. Epicercal - Upper caudal lobe larger
  3. Hypocercal - Lower caudal lobe larger
8. Placoid scales - modified to form teeth
9. Lateral line system - sensory
10. Ampullae of Lorenzini
  1. Electroreceptors in head and pectoral fins
  2. Pits below epidermis containing conductive glycoprotein
11. SHARKS
  1. ~360 spp 2 lineages(poss4+)
    1. SQUALOIDS (basking sharks, megamouth)
      1. Deep cold water
    2. GALEOIDS (Requiems, hammerheads)
      1. warm shallow seas
  2. Hyostylic Jaw Suspension
    1. Cranial kinesis. Elastic ligaments
    2. Platoquadrate teeth - recurved, stout, highly serrated
  3. Reproduction
    1. Internal fertilisation
    2. Small numbers - well provisioned offspring
    3. Lecithotropy - yolk in egg
    4. Matrotrophy - reproductive tract
    5. Oviparous - mermaid's purse
    6. Ovoviparous - egg retention, eggs move to uterus, hatch & stay
      1. Milky substance in uterus, pass through offsprings' mouth and gills for nourishment.
12. BATOIDS (skates and rays)
  1. Skates - thick, paired dorsal fins, caudal fin, oviparous
  2. Rays - whiplike, serrated dorsal barbs, viviparous
  3. ~456 spp -early divergence from sharks
    1. Dorsoventrally flattened - bottom dwellers
  4. Generating electricity
    1. intracellular fluid 84mV -ve extracellular. Na+ exclusion. Smooth surface depolarises. Rough surface stays -84mV. Na+ flows -> +67mV
  5. Teeth - flat crowned plates
    1. Specialised mouth - mollusc and crustacean diet
  6. enlarged pectoral fins - thrust
13. HOLOCEPHALIANS
  1. ~35spp
    1. diverged from sharks ~360mya
  2. Anatomically odd mix
  3. Shark like & boney fish
  4. ground dwelling, deep water.
  5. Autostylic jaw - mixed diet, fused tooth plates
  6. Oviparous - cephalic claspers
  7. poisonous spines

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Chondricthyes - Cartilaginous Fish

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	Creado por Litty Carter hace más de 11 años