Historical
The term Pleistocene ("most recent") was coined by Charles Lyell in 1839, on the basis of a section of type strata in eastern Sicily, according to the proportion of extinct to living species of mollusk shells in the sediment. Strata with 90 to 100% present day species were designated Pleistocene. Clearly this is a somewhat arbitrary arrangement, and in any cases many strata do not contain mollusk shells.

The present definition of the Pleistocene is based on radiometric dating of 1.6 million years or more recent, the presence of cooler water mollusks and foraminifers, the absence of marine micro-organisms called discoasters, and on land the fossil remains of modern horses and true elephants (in the past more widespread than they are today).

Geography and Climate
About a third of the way into the Pleistocene the first Ice Age hit. There were a series of advances and retreats of the ice as the climate fluctuated between cold (glacial) and warm (interglacial) periods. The sea level rose during the melting of the glaciers, then dropped again during the next long cold spell (ice formation). The lowered sea levels formed land bridges that enabled the migration of animals and humans across continents.

Smilodon, the great saber-tooth cat, lived in North America and was as large as a lion.

The Pleistocene saw the age of mammals is at its height, with both small and giant forms living alongside each other. Animals and plants are basically modern species, although distributions were unusual; e.g. hippos and elephants in what is now London during the warm interglacial periods. There were however many giant mammals - the so called megafauna - which evolved and lived on all the worlds continents. In Australia for example there were giant kangaroos and wombats (as well as a number of forms with no living relatives), in Europe the mammoth and woolly rhinos, in America the mastodon, camels, and dire wolves, in South America elephant-sized ground sloths and giant armadillo-like creatures called glyptodonts.

Intelligence
During the Pleistocene the hominid intelligence continued. Homo erectus, Homo neanderthalis, and finally modern man (Homo sapiens) succeeded each other in time (although modern man and neanderthals lived alongside each other in Europe for a short period. Neanderthal man had as large a brain capacity as modern man, but still died out. With language and the sharing of knowledge the humans had an edge for survival. There is some argument over whether neanderthal man had language or not . Most sciantists think they did. With language came concepts, ideas, and survival stratigies.

The Calabrian Age includes all of the Pleistocene Epoch. However, geologists and anthropologists speak informally of an Early, Middle and Late Pleistocene.

The information of this page came from http://palaeos.com/

For more on the Cenozoic periods go to http://palaeos.com/Cenozoic/Cenozoic.htm

Page uploaded on WebDyer Site on 10 June 2004 , last modified 10 June 2004
text content © M. Alan Kazlev 1998-2002

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