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      (dng)ǰλãAԇW(wng) >> иԇ >> иo(do) >> иx >> иԇиxvx12

      иԇиxvx12

      AԇW(wng)   2013-07-29    С

      2. x----xcЧx

      (1) xеԔԽY(ji)-----SKIMMING

      1) ҪԔ(x)xă(ni)

      Ø Y(ji)(gu)wă(ni)

      Ø e|(zh)ĸ

      Ø }Ŀӳԭĵă(ni)

      2) Կٞg[ă(ni)

      Ø Ĕ(sh)(j)

      Ø @e: ζe,ew,Y(ji)λ

      Ø (du)\xһ

      Ø ׌\D(zhun)xһ(D(zhun)Ժһ)

      (2) λU(ku)x߉݋Ę(gu)----ģՓ

      1) xеĐ(x)----ָx\•x\x\ҕǸ߶^\x

      2) λx߉݋

      Ø Ӵλ,׃~ȺM----c(din)Ӗ(xn)

      ԺϲȺijɷ:

      ² ~

      ² ~Z

      ² ~Z

      ² ^ZIJʽ

      ² Z^Z^ZeZ

      ² ̶

      : Generally, in order to be preserved in the fossil record, organisms must prosess hard body parts such as shells or bones. Soft, fleshy structures are quickly destroyed by predators or decayed by bacteria. Even hard parts left on the surface for certain length of time will be destroyed. Therefore, organisms must be buried rapidly to escape destruction by elements and to be protected against agents of weathering and erosion. Marine organisms thus are better candidates for fossilization than those living on the land because the ocean is typically the site of sedimentation, whereas the land is largely the site of erosion.

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