Notes: 1  In 1997, MLB retired Jackie Robinson's number 42 meaning no other player in MLB could ever wear it. However, it was grandfathered to anyone who was currently wearing the number. 2  Mariano Rivera is the only Yankee to appear as an active player while wearing his retired number.
The Ordovician Period. The Ordovician Period lasted almost 45 million years, beginning 488.3 million years ago and ending 443.7 million years ago.* During this period, the area north of the tropics was almost entirely ocean, and most of the world's land was collected into the southern supercontinent Gondwana.
Prehistoric (Archaeological) & Historic Periods. The Prehistoric Period consists of time periods in the origin and evolution of humankind from about 2.5 million years to about 900 BCE. the Prehistoric Period is divided into the Archaeological Periods of the Stone, Bronze and Iron Ages.he time from the origin of the earth to the present is divided into super eons, eons, eras and periods. The Precambrian period is a super eon that is sub-divided into three eons: â¢ the Hadean Eon (4.5 to 3.8 billion years before present), â¢ the Archean Eon (3.8 to 2.5 billion years before present),, and.