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Fossils - Coggle Diagram

- - - - Secrets collagen to attach themselves to the sea floor, upright position with hinge at base. elongate shell, equal valves and flattened ventral surface to support and stabilize the shell.
    - - Thick unequal sized valves and a single large adductor muscle, fixed to the sea bed by a larger left valve
    - - Flat, Elongated and smooth shells allowing for easier penetration of sediment. Valves are equal in size
    - - Very thick and convex left vales for stability.
    - - equal in size, more convex and less elongate and smoother than deep burrowers
    - - Unequal sized valves but nearly bilaterally symmetrical. Shells consist of coarse ribs and one large adductor muscle
- - - - Large eyes (360) to aid hunting and avoid predators
      - Large glabella which could be filled with gas to aid buoyancy
      - Elongated and streamlined body to aid movement
      - Large pygidium, used as a paddle
    - - Small or no eyes - adapted to dark or murky bottom water conditions
      - Wide body and Large genal spined to help distribute body weight
      - Large cephalon with reinforced marginal fringe which could be used as a shovel to break up sediment
    - - large eyes to aid hunting and avoid predators
      - Large body to overcome prey
      - Large Glabella to allow storage of digesting food
      - thoracic spines which could be used to stab and pin prey
    - - Elongated, streamlined thorax with poorly developed thoracic spines, again to allow easier movement
      - Small or no eyes, sometimes the eyes were on stalks to allow the creature to see while remaining buried in shallow sediment
      - Smooth convex cephalon and poorly developed or no genal spine to allow easy movement through sediment
      - Ridges on the pygidium indicated a trilobite that would burrow backwards, and would use the ridges to generate frictional resistance
  - - - diagonal sets of walking trails, sideways crab like motion
    - - ovoid surface scours, resting nests or surface burrows
    - - chevron-like trails which are formed by a trilobite crawling, ploughing, shoveling or burrowing through soft sediment
    - - walking or striding tracks with individual leg impressions
- - - - The mold becomes infilled by a mineral precipitate to form a cast
      - Ground water flow
- - - - Large range of fossil sizes
    - - No orientation of elongated fossils
    - - Whole, Complete or unfragmented
  - - - Often Fragmented/ Incomplete
    - - Orientation of elongated fossils can be observed
    - - Small size range of unfragmented or fragmented fossils
- - - - Proterozoic
        
        Phanerozoic
        
        1200ma: Evolution of multi cellular life
        
        600ma: First Complex animals
      - 3800ma-4000ma: Single Cell life