It has no individual name
Procession of the Equinox
There was one spercontinent called Pangaea, which consists of all of the current continents joined together. It existed until 250 million years ago, where it splitted up into Laurasia and Gondwanaland, and further splitted into the current seven continents.
The five mass extinctions that occurred in Earth's history took place during the Ordovician period (about 445 million years ago), the Devonian period (about 375 million years ago), the Permian period (about 251 million years ago), the Triassic period (about 200 million years ago), and the Cretaceous period (about 66 million years ago).
A comet with a period of 200 years or more.
150 millions years ago Earth was in the late Jurassic period.
It has no individual name
That is the correct spelling of the period of "twenty-seven years" (27 years).
Nothing happens seven years after a girl has her period. There's nothing specific about this length of time.
sevennenium
generation
french and indian war
100 years is a "century."
Twenty years is a score, as in "Fourscore and seven years ago..." Fourscore and seven equals 87.
term millennium
A decade.
It has been seven years since the first Call of Duty came out.
Its called a century! century means 100 years and decade means 10 years