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Dinosaurs: The extinct reptiles commonly known as dinosaurs appeared about 225 million years ago and became extinct about 65 million years ago. Although some dinosaurs were gigantic, others were relatively small, about the size of a chicken. It is believed that birds evolved from one of these species of small dinosaur. |
Reptile and bird eggs: Dinosaurs laid eggs rather like those of living lizards, crocodiles and turtles. Some reptile eggs are soft and leathery whereas others have a hard shell, like that of birds' eggs. The egg shells of large birds (such as the ostrich) and large dinosaurs are quite robust, consisting of several layers of mineral material, which lends itself to fossilization. |
click
here to view image
Eggs of various modern
reptiles and birds:
Top row: crocodile and
two different kinds of tortoise.
Lower row: ostrich, goldcrest
and Aepyornis
(the extinct elephant bird
of Madagascar).
All to same scale.
The ostrich egg is 145mm
long.
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