Early vertebrates and Primitive fish

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Vertebrate Zoology (Early vertebrates/primitive fish) Mind Map on Early vertebrates and Primitive fish, created by Litty Carter on 23/04/2013.
Litty Carter
Mind Map by Litty Carter, updated more than 1 year ago
Litty Carter
Created by Litty Carter almost 11 years ago
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Resource summary

Early vertebrates and Primitive fish
  1. What is a fish?
    1. All vertebrates which aren't tetrapods
      1. Aquatic vertebrate
        1. (appendages - fins)
          1. Gills
            1. Aquatic vertebrate
              1. Paraphyletic group
              2. Skin with scales of dermal region
              3. Early vertebrates
                1. Early Cambrian fossils (535mya)
                  1. China - lack mineralised tissues
                  2. Heart and fin rays
                    1. Mineralised tissue - late Cambrian
                    2. CONODONTS
                      1. Microfossils made of Apatite: Cambrian-Triassic
                        1. Similar to dentine
                        2. Diet: Marine algae/inverts
                          1. Many vertebrate characteristics
                            1. (but no gill slits)
                              1. Diffusion?
                              2. MINERALISED TISSUE
                            2. Agnatha
                              1. (Jawless fish)
                                1. Hagfish & Lampreys
                                  1. Hagfish (Myxinoidea)
                                    1. ~ 65 spp (all marine)
                                      1. Scavengers & predators
                                      2. Single nasal opening. Single semi-circular canal
                                        1. Degenerate eyes (skin covered)
                                          1. Mucoid bag
                                            1. Skewed sex ratios (100:1)
                                              1. Eggs with tough covering and attachment hooks
                                              2. Colonial/semi-colonial
                                              3. Lampreys (Petromyzontia)
                                                1. 41spp ( ~50% parasitic)
                                                  1. Marine & freshwater
                                                  2. Cartilage pipe around notochord (Arcualia)
                                                    1. Simple digestive system
                                                      1. Well developed kidney
                                                      2. Oral gland anticoagulent
                                                        1. 2 semicircular canals
                                                        2. Chloride cells gills : tidal ventilation
                                                    2. No scales
                                                      1. Eel like bodies
                                                        1. No distinct stomach, jaws or vertabrae
                                                          1. Cartilaginous
                                                            1. 5-16 pairs of gills
                                                              1. Distinct Brain
                                                              2. Ostracoderms
                                                                1. Anapsids
                                                                  1. relationship in flux
                                                                  2. Lacked jaws - movable mouth plates
                                                                    1. filter feed / soft bodied prey
                                                                    2. midline dorsal fins & some pectoral
                                                                      1. Extinct: late devonian
                                                                      2. Jawless to Jaws
                                                                        1. Major evolutionary step: changes in habitat/behaviourresources
                                                                          1. 1. Ancestral Agnathan: unjointed branchial arches
                                                                            1. 2. Jointed branchial arches increase ventilation
                                                                              1. 3. Mouth closing ventilatory jaws
                                                                                1. 4. Early jawed Gnathostome
                                                                                  1. Improved locomotion, sensory and ciculatory systems
                                                                                    1. Silurian -> mid Ordovician
                                                                                      1. 2nd Hox duplication event
                                                                                        1. Enlarged forebrain
                                                                                          1. Lateral line system
                                                                                            1. 4 recognised clades
                                                                                      2. Gnathostomata
                                                                                        1. Class: Placoderms
                                                                                          1. Plated skin
                                                                                            1. Plates hinged
                                                                                              1. Internal skeleton: bone & cartilage
                                                                                            2. Plated teeth: Ptyctodontids
                                                                                              1. Early specimens - no teeth. Later on - true teeth
                                                                                              2. Primarily marine but some in estuaries and fresh water
                                                                                                1. Primary benthic - dorsoventrally flattened
                                                                                                  1. External pelvic appendages
                                                                                                2. Class: Acanthodians
                                                                                                  1. Many short spines and ventral fins
                                                                                                    1. Slender bodied
                                                                                                    2. Mid Ordovician
                                                                                                      1. Scales and heterocercal tail - primarily midwater
                                                                                                        1. No teeth - filter feeders
                                                                                                        2. Class: Condrychthyes (cartilaginous fish)
                                                                                                          1. Subclass: Elasmobranchii
                                                                                                            1. Sharks, skates, rays
                                                                                                            2. Subclass: Holocephali
                                                                                                              1. Chimaeras & ghost fish
                                                                                                            3. Osteichthyes (bony fish)
                                                                                                              1. Class: Sarcopterygii
                                                                                                                1. Lobe finned fish
                                                                                                                2. Class: Actinopterygii
                                                                                                                  1. Ray finned fish
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