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It was during the Paleoproterozoic that small islands of crust were first stitched together to form the stable nuclei of the continents we know today.

India has a similar history. Similarly, India appears to be an amalgamation of four cratons.

The formation of Baltica - the continent which was to become Europe -- is one of the best-known examples. Baltica formed in the Paleoproterozoic from the fusion of three cratons

five-ton animal the size of a car, with a giant bony frill on its head, and you've got a fairly accurate picture of a ceratopsian dinosaur such as Triceratops.

are found only in the Late Cretaceous of North America; they are among the last of the dinosaurs (other than the birds of course).

Ceratopsians were ornithischians, or "bird-hipped" dinosaurs.

The Proterozoic Eon extended from 2.5 billion to 541 million years ago and is often divided into the Paleoproterozoic (2.5 billion to 1.6 billion years ago), the Mesoproterozoic (1.6 billion to 1 billion years ago), and the Neoproterozoic (1 billion to 541 million years ago) eras.

Megascopic eukaryotes first appeared about 2.3 billion years ago and became widespread by about 1.8 billion years ago.

Eukaryotes employed a form of respiration and oxidative metabolism; they had a central nucleus that could split into separate sex cells, and so for the first time a mixed and variable genetic code could be passed to younger generations.

Online exhibits : Geologic time scale The Archean Eon and the Hadean The Archean eon, which preceded the Proterozoic eon, spanned about 1.5 billion years and is subdivided into four eras: the Neoarche

The Quaternary Period is a geologic time period that encompasses the most recent 2.6 million years — including the present day. Part of the Cenozoic Era, the period is usually divided into two epochs — the Pleistocene Epoch, which lasted from approximately 2 million years ago to about 12,000 years ago, and the Holocene Epoch, which began about 12,000 years ago

About 65 million years ago the second greatest mass extinction in Earth history occurred, resulting in the loss of the dinosaurs as well as nearly 50% of all the world’s species. Though not nearly as severe as the end-Permian mass extinction, the end-Cretaceous extinction is the most famous mass extinction in Earth history

Terrestrial plants also suffered a major extinction at this time; in some regions up to 60% of latest Cretaceous plant species were absent in the subsequent Paleocene.

The causes of the end-Cretaceous extinction are still being debated by paleontologists. Researchers agree that a major factor was an asteroid about 10 kilometers in diameter that struck what is now the Yucatán peninsula in Mexico. The effects of the impact were catastrophic, probably including global forest fires, possibly a period of cold weather due to sunlight-blocking dust and smoke, and a subsequent period of hot climate caused by the high levels of CO2 released into the atmosphere by the impact.

Found between 3.85 and 2.95 million years ago in Eastern Africa (Ethiopia, Kenya, Tanzania),

Similar to chimpanzees, Au. afarensis children grew rapidly after birth and reached adulthood earlier than modern humans. This meant Au. afarensis had a shorter period of growing up than modern humans have today, leaving them less time for parental guidance and socialization during childhood.

Au. afarensis had both ape and human characteristics: members of this species had apelike face proportions (a flat nose, a strongly projecting lower jaw) and braincase (with a small brain, usually less than 500 cubic centimeters -- about 1/3 the size of a modern human brain)