The Cambrian Period: (570 million years ago)
The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears. It was once thought that the Cambrian rocks contained the first and oldest fossil animals, but these are now to be found in the earlier Vendian strata.
Climate
The climate at the beginning of this period was cold, but over time the climate in all parts of the Earth grew warmer. This made the seas a good place for many species to live. The continents were still forming. They were mostly barren rocks. The land had no plant or animal life on it yet.
The Trilobites
One species was so plentiful and had such great numbers and so many species that it is sometimes called the ruling species of the period. This species was the Trilobite.
A Trilobite
Trilobites on the sea bed
Other Invertebrates
There were plenty of other species living during the Cambrian Period also. Mollusks, worms, sponges and echinoderms filled the Cambrian seas. These were the main occupants of the planet at this time. It would take a few million years for animals with backbones to appear
The End of the Cambrian Period
The Cambrian Period began with an explosion of life forms. It ended in a mass extinction. Advancing glaciers would have lowered the temperature of the shallow seas where so many species lived. Changes in the temperature and the amount of oxygen in the water would have meant the end for any species that could not adapt.
Map of the Earth during the Cambrian Period
Time Line
- Cambrian period: (570 million years ago)
- Ordovician period: (505 million years ago)
- Silurian period: (438 million years ago)
- Devonian period: (408 million years ago)
- Carboniferous period: (360 million years ago)
- Permian period: (286 million years ago)
- Triassic period: (245 million years ago)
- Jurassic period: (208 million years ago)
- Cretaceous period: (144 million years ago)
Categories
Dino Facts............
Tyrannosaurus rex (T-REX) means "Tyrant Lizard King".
T-Rex stood 40 feet long and weighed 5-7 tons. Its jaws were about 4ft long and its teeth grew up to 13 inches in length.
The Velociraptor was very small compared to other Dinosaurs of the time. It stood only 6 feet long. It was a pack hunter. Recent discoveries show that the Velociraptor had feathers!