Evidence for Evolution
- Created by: amazingashers
- Created on: 22-11-16 17:54
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- evidence for evolution
- a fossil is any trace of an animal or plant that lived and died long ago
- fossils can be formed in three ways:
- from gradual replacement by minerals
- things like teeth, shells and bones don't decay easily so they can last for ages when buried.
- they are then eventually replaced by minerals, forming a rock-like substance shaped like the original hard part.
- the fossil stays distinct inside rock until it is dug up
- they are then eventually replaced by minerals, forming a rock-like substance shaped like the original hard part.
- things like teeth, shells and bones don't decay easily so they can last for ages when buried.
- from casts and impressions
- fossils can form when an organisms buried in soft material like clay.
- the clay then hardens around it and the organism decays, leaving a cast of itself
- things like footprints can be pressed into these soft materials, leaving an impression when it hardens
- the clay then hardens around it and the organism decays, leaving a cast of itself
- fossils can form when an organisms buried in soft material like clay.
- from preservation in places where no decay happens
- this is because the conditions arent suitable for microbes to work
- in glaciers it is too cold
- in peat bogs it is too acidic
- in amber there is no oxygen or moisture
- this is because the conditions arent suitable for microbes to work
- from gradual replacement by minerals
- fossils found in rock layers can tell us three things:
- what the creatures and plants used to look like
- how long ago they existed
- generally the deeper the rock, the older the fossil
- how they have evolved
- from studying the similarities and differences between fossils in differently aged rocks, we can see how species have changed and developed over billions of years
- the fossil record is incomplete, this is because:
- very few dead plants or animals actually turn into fossils, most just decay away.
- some body parts, like soft tissue, tend to decay away completely
- there are fossils yet to be discovered that might help complete the overall picture
- the pentadactyl limb is evidence for evolution
- a limb with five digits
- in many species, mammals, reptiles, amphibians
- in these species the pentadactyl limb has a similar bone structure but has a different function
- the similarity in bone structure provides evidence that species with a pentadactyl limb all derived from a common ancestor.
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