Monday 27 January 2014

FOSSIL PLANTS



Click here for the 'Seeds of Eaden' seed shop

Fossil plants tell us a story about the vegetation that existed millions of years ago, and how plant species have evolved over those years.

Plant tissues are very delicate, especially the leaves and flowers. Because many plants live on land there are few fossil remains as most fossils are formed in sedimentary rocks.  Plants on land are exposed to much weathering, even if they are covered with sediment.  Tissues break up as they die and roots and stems can be preserved in  different locations. 

Plant fossils found are often black carbon films left on bedding surfaces. On occasion three dimensional fossils are found. Pollen grains fossilise very well, and have enabled scientists to recognise many plant species. 

Plant fossils enable us to reconstruct the environment in which they lived.  Plants are very specialised and can often indicate the climate in which they lived. Fossil records show that some plant species disappeared with changes in climate. 

The earliest plant fossils to be discovered were algae on rocks (stromatolites) from the Cambrian period 500 million years ago.  These showed an important stage of the earths development when the first oxygen was released into the primitive atmosphere.

Simple vascular plants evolved in the Silurian period over 400 million years ago.  During the Devonian period plants became commonly green.  During the carboniferous period 300 -350 million years ago great forests were formed. Many plants that we are familiar with today developed 5 - 20 million years ago during the Cenozoic era.

Flowers developed quite late during late Mesozoic period 200 million years ago.  They enabled plants to cross pollinate which was significant as it led to genetic diversity.  Nectar and pollen from flowers also provide food for insects, which quickly evolved after.

A true living fossil is the Williamsonia pine, which existed in the Jurrasic period.   It was thought to be extinct but then living plants were discovered in recent times.  Now the pine has been propagated and can be bought readily in garden centres as a living fossil.

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Where are fossils found?


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