The Earth's History is broken up into a
hierarchical set of divisions for describing geologic time. They
were broken up in to increasingly smaller units of time. The
generally accepted divisions are eon, era, period and age. The units
were the Precambrian and Phanerozoic. The Precambrian was divided
into three major divisions, Hadean Archean and Proterozoic. The
Phaneozoic Era was divided into three major divisions, Paleozoic,
Mesozoic and Cenozoic. At the time of the Dinosaurs, it was the
Mesozoic Era. The Mesozoic Era was like the middle age of life. The
Mesozoic Era started abround 245 million years ago and it lasted
about 180 million years. During the Mesozoic Era, the super
continent known as Pangea, which formed during the Paleozoic Era,
was beginning to break apart into smaller continents. During the
Mesozoic Era, the dinosaurs were evolving and dominating, causing
the Mesozoic Era to also be known as the age of the reptiles.
dinosaurs and the mammals appeared during
period, roughly 225 million years ago.
The dinosaurs went
extinct 65 million years ago.
Mesozoic is divided into three periods: the Triassic, Jurassic and
Cretaceous Era. At the start of the Triassic Era, there was an
enhanced extinction that changed the marine life. They discovered
that ninety five percent of the marine species were gone. By the end
of the Triassic, dinosaurs had spread rapidly through the land
ecosystems on Earth. It was during the Jurassic that many of the
most famous dinosaur species had evolved. They evolved quickly and
adapted. There was evidence that the first bird was evolved during
this era.It was a fossil record that showed it. It is believed that
a combination of volcanic activity and an asteroid impact around 65
million years ago was the cause of the extinction of the dinosaurs,
and many other species that were living in the Mesozoic Era.