Radiometric dating of ordovician period
The geological or deep time of Earth's past has been organized into various units according to events which took place in each period.Different spans of time on the time scale are usually delimited by major geological or period is defined by the Cretaceous Tertiary extinction event, which marked the demise of the dinosaurs and of many marine species.Older periods which predate the reliable fossil record are defined by absolute age.Each era on the scale is separated by a major and/or changing event.**If the images and/or text on any of the web pages do not appear evenly spaced and centered on your screen, which commonly occurs with AOL pages, maximize the individual page's window. Within three weeks, there will be nothing left but a few small bones." A fossil normally preserves only a portion of an organism, usually that portion that was partially mineralized during life, such as bones and teeth.
Fossils, by definition, are the remains or traces of organisms that lived at least 10,000 years ago.
to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth.
The table of geologic time spans presented here agrees with the dates and nomenclature proposed by the International Commission on Evidence from radiometric dating indicates that the Earth is about 4.570 billion years old.
The oldest uncontested fossils on earth are 2 billion year-old stromatolites in Minnesota, Wisconsin, and Ontario.
Scientist Olivia Judson provides this good example of what happens to an adult male gorilla in the tropical rainforests of the Congo; "An adult male gorilla— all 330 pounds of him—will be reduced to a pile of bones and hair within 10 days of his death.
What scavengers like vultures and hyenas leave behind, flies, ants, worms, and bacteria quickly consume.