First Children Encyclopedia

(Marvins-Underground-K-12) #1
How was it made?

Can you name some of the things that fossilize?


206


Age of the dinosaurs


Fossils may form when animal or plant matter is buried


soon after death under mud or sand. However, that’s just


the beginning of a process that takes millions of years.


70 million years ago
A T. rex has died and is
washed downstream. It rests
on layers of soft mud and is
rapidly buried.

Five years later
The creature’s soft flesh has
slowly rotted away, leaving
the bones. Over time these
begin to move apart.

50 million years ago
A sea has now spread over
the area once occupied by the
river. Heavy pressure is slowly
turning the sand to sandstone.
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