Middle Life

Middle Life

245 to 65

Million Years Ago

T.Rex skull reconstructed at the Field Museum of Natural lHistory, Chicago. Copied from Wikipedia under the Creative Commons Attribution 2.0 License.

The Age of the Dinosaurs

After the Great Dying Earth once again was balmy and warm almost everywhere. Reptiles thrived, and early mammals, a class of warm-blooded animals evolved which had hair and differentiated teeth, laid eggs containing partially developed embryos and produced milk for their young. These shrew-like animals, survived in inconspicuous niches away from the powerful and prolific reptiles. It was dinosaurs, not the brainier mammals, who gained ascendance first and ruled the world for more than 140 million years.

Dinosaurs Reign

208 million years ago

A palaentologist chips rock from dinosaur vertebrae. A United States National Park image in the public domain.

Dinosaurs, the "Terrible Lizards," subjugated the world for more than 140 million years, and survived for at least 160 million. At first they were small and agile meat-eaters, but over the millions of years of their domination, they came in all sizes. They weren't beautiful, and their brains were small, but they were strong and often big, and they survived a very long time.

Our knowledge of dinosaurs is derived from the work of palaeontologists, as in the picture, recovering and preserving their fossilized remains.

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Dinosaurs

Flowers and Fruit Blossom

150 Million years ago

True birds began to evolve at this time and today may be the only remnants of the once mighty dinosaurs. Insects, which already had been around for quite a while, were now diversifying. 120,000 species of flies, mosquitoes, gnats, midges, and no-see-ums, along with moths, bees, ants and aphids all flourished.

Spittle bug. Photograph by Dave, aka "Pollinator". Picture released under GNU licence.

Copyright P.L. Sissons. For conditions of use see Copyright and Acknowledgements link on the home page.

Insects and flowering plants began to develop a partnership that even today is important to our welfare.

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How The Garden Grows

Oil and Chalk

145 million years ago

About 250 million years ago continental drift had created one great land mass stretching between the north and south poles called Pangaea ("All land"). 145 million years ago this broke up and the continents we know today began to take shape. Volcanoes are more frequent when the tectonic plates are moving and the unsettlement of this time contributed to massive deposits. Crude oil was formed when plankton living in the warm waters died and decayed, and chalk deposits are the remains of marine animals.

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Buried Treasure

Placental Mammals

125 million years ago

Scientists were overjoyed at the discovery of the fossil of a five inch mouse that had lived in China 125 million years ago. It was a mother mouse and the earliest fossil of a placental mammal that has ever been unearthed. It means that placental mammals, which do not lay eggs but give birth to live young, were living on earth with the dinosaurs for 60 million years. When the dinosaurs died, mammals took their places.

This is a public domain image from the US National Institute of Health

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The Dawn Mother

K-T Boundary Extinction

65 million years ago

Aerial photograph of Crater Lake by W.E. Scott. A United States Geological Survey image, in public domain.

It is called the "K-T Boundary Extinction" because it marks the end of the Cretaceous Period or era of chalk known as Kreide in German, and the beginning of the Tertiary period. It may be the most famous extinction, for it is the one that killed the dinosaurs. Mysteriously, many mammals and birds were relatively unscathed.

It is not known what caused this extinction; scientific speculation ranges from a meteor impact in Mexico to a super-volcanic explosion. The above picture, Crater Lake in Oregon, is illustrative of the effects of a super-volcanic type eruption. Mount Mazama collapsed in on itself to form a deep lake, technically a caldera.

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A Meteor Impact

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The background picture to the page title is a Corel Draw image of chalk cliffs.