Essay - Current Knowledge on Two Billion Year-old Fossils the Current News...

CURRENT KNOWLEDGE ON TWO BILLION YEAR-OLD FOSSILS

***** current news on our knowledge of fossils from the Pre-Cambrian Period, roughly some two billion years ago, has grown by leaps and bounds. Most paleontologist today that study invertebrate fossil remains, especially those that lived on Earth during a time when life on l***** was virtually non-existent, are rather convinced ***** the earliest evidence for life evolved ***** at least 3.8 billion ***** ago which coincides with ***** generally accepted idea that meteorites somehow brought along the basic ingredients for ***** to a then-sterile planet Earth.

Stephen K. Donovan, a scientist at Johns Hopkins University in Baltimore, Maryland, said only ***** weeks ago ***** "the existence of various organic compounds, such has RNA and DNA, suggests th***** life has a common *****nces*****r, but there ***** many th*****gs we do not yet know, such as the ***** of origination and the history of diversification in the ***** environments." Donovan added that "the oldest *****ll-preserved specimens are ***** Isua in west Greenland which date from about 3.8 billion years ago." This period, *****n as the Archaean, w***** characterized by much volcanism and active tectonics which *****dicates ***** the ***** was heating up.

The Proterozoic Period seems to have occurred rather spontaneously, but over hundreds ***** millions of years, ***** ***** a shift to a more st*****ble tectonic state which created continents ***** interior-based continental seas. One of the most important outcomes of this action was "the introduction of oxygen by photosyn*****sis, ***** exactly how fast this occurred is unknown, but good quantities were most probably present around 2 billion years *****" (Vidal, 156).

***** th***** time, a number ***** ***** *****ms emerged and left behind three types of fossils—body, trace and chemical, which can be readily found within rocks formed ***** the ***** and Proterozoic Periods. Some ***** these fossils are actual cellular remains, something which Donovan admits is extremely rare in rocks of this age. The oldest ***** been *****d as ***** 3.5 billion ***** and ***** be found ***** cherts from the Warrawoona Gro***** near ***** North Pole, being northwest of Australia, and in the Onverwacht Group ***** eastern Transvaal (South Africa).

These fossils are "filamentous, while cocooids have also been reported from the North *****. In the region of Lake Superior in northern Michigan, gunflint chert has revealed various bacteria which is exceptional, due to most Proterozoic ***** being cyanobacteria which have tough exterior coats that preserve quite well" (Corfield, 178).

Although the scientific jargon of invertebrate paleontologists, ***** those that ***** micro-fossil remains, is ***** hard to understand, Dr. Edward Landing, a specialist in the study of such *****, told the press ***** "fossil cells are exceedingly rare, and the main evidence for life during ***** Archaean and ***** ***** is based on stromatolites, a special type of trace ***** formed ***** the binding ***** trapping of sediment of microbial mats, e*****ly phototactic cyanobacteria" (*****43).

*****. Landing also mentioned that chemical fossils hold much potential. Scientifically speaking, there are two