The remains of ancient animals and plants, or as they are called by paleontologists, “fossils” – are an evidence of biological evolution, by which we know how fauna and flora of the Earth has been changing through centuries. They are stored in the form of fossilized parts of bodies or prints on hard rocks. However to be etched in eternity was not designated for every creature. The greatest chance appears for those who possess a solid skeleton: internal, as for vertebrates, or external, such as cameo shells.
But “lucky” for fossilization were only those which remnants managed to avoid total destruction, were isolated from microorganisms, currents, winds and temperature extremes. Such conditions often develop in stagnant ponds or shallow seas. Most of the ancient fossilized plants and animals formed precisely in such places.
The process of fossilization looks as the following. For thousands of years, minerals gradually filled all cavities and replaced the original organic and inorganic matter, having created a stone copy, which, in a result of tectonic processes and erosion, was found on the surface and appeared to the attention of people.
Fossils of soft tissues are much less common, but they have opened to us a wonderful world of the ancient Precambrian (from the formation of Earth about 4600 million years ago to 540 million years ago) multicellular creatures. According to Shepherd, “the earliest reported fossil discoveries date from 3.5 billion years ago” (“What is a fossil?”). Also insects solidificated in amber (congealed plant resin), ancient mammals drowned in the pits of the thickened oil – “asphalt traps”, as well as frozen in permafrost – belong to fossils. These fossils have not yet had time to turn into stone, so they can preserve biopolymers and even details of the structure of tissues.
Works Cited
Shepherd, Roy. What is a fossil? Discovering fossils. n.d. Web. 30 Oct 2013.
http://www.discoveringfossils.co.uk/whatisafossil.htm
“Fossils”. Nature BBC. n.d. Web. 30 Oct 2013.
http://www.bbc.co.uk/nature/fossils
