to what date, can the earliest fossils be traced?
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The oldest fossil evidence for life on Earth is found in 3.5 billion year old rocks in the Pilbara region of Western Australia. Along with rocks of similar age in South Africa these are the oldest well preserved sedimentary rocks known. The evidence for fossil life takes the form of: \n\nstructures called stromatolites which are believed to be the fossilized remains of laminated structures built by colonies of micro-organisms. Modern examples of such colonies are found in Shark Bay in Western Australia \nmicrofossils of individual micro-organisms. \ncarbon isotope ratios indicative of biological activity. \nSome recent results include the discovery of 3.45 billion year old stromatolites by scientists of the Geological Survey of Western Australia, and the reporting of microfossils from a deep sea hot spring deposit of age 3.2 billion years by Birger Rasmussen of the University of Western Australia.\n\nWhile controversy surrounds many of the reports of fossils of this age, it is generally accepted that there is sufficient evidence to be reasonably sure that life was well established on earth at about 3.5byr ago. Older rocks at 3.8byr age in Greenland are too greatly deformed to preserve fossils but have been claimed to show evidence for life in their carbon isotope ratios.\n+\nFUNGI and algae first teamed up to form lichen 600 million years ago, according to newly discovered fossils from China. This makes them slightly older than the first fossils of complex soft-bodied animals, and far older than land plants.\n\nLichens are the product of a symbiotic relationship between algae, which produce food, and fungi, which provide moisture, nutrients and a protective framework. The new fossils come from south China, and were laid down in shallow seawater (Science, vol 308, p 1017).
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It is a huge question, but in general you would want to check paleoclimatology (for example, glaciation of Antarctica after opening of Drake and Tasmania passages), paleontology/biogeography (distribution of fossils and ancient migration of various animal groups).\n\nThere is a page with lecture notes which is very shorthand but touches on most things you may want to check:\nhttp://jersey.uoregon.edu/~mstrick/RogueComCollege/RCC_Lectures/ConDrift_PlateTec.html\n\nAnother link that touches on the subject:\nhttp://pgap.uchicago.edu/PGAP2000-1.html
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try wikipedia, search fossils
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Actually, there's a very simple explanation.\n\nDinosaur fossils have been around for tens of millions of years.  They include fossilized bones and teeth, but also fossilized impressions of skin and footprints.  \n\nThousands of years ago, our ancestors stumbled uppon such fossils just as we do today.  They knew nothing about bones turning to rock and they certainly had no idea about the age of these things.  The fossils could have been a month old or a decade.  Still, they never saw any living dinosaurs.\n\nThey made the best assumption that they could - there were huge lizard beasts that used to be common but now were rare.  All of them - some with feet, some without, some with wings, some without - got lumped together, thrown into the blender of folklore and came out as dragons.\n\nAnd since dinosaur fossils are everywhere on earth, dragon myths are everywhere as well.\n\nNow, doesn't that make sense?
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OK, first geography is NOT geology *sigh*\n\nLook up carbon dating; you can either tell by the degradation of carbon or by basic layering (what's on the bottom is older than what's on the top).
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Actually, bacteria weren't the first organisms to inhabit our earth.  Simple-celled prokaryotes that pre-dated bacteria have been discovered in the oldest fossils ever recorded.  It's believed by some that life even existed before these prokaryotic cells, however fossils of these events do not exist (the oldest fossils date 3.5 billion years ago, and are of prokaryotic cells - bacterial fossils started showing up dating only 2.7-3.0 billion years ago).
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All fossils should have some Carbon-14, but hypothetically, if one didn't, a different radioactive isotope could be used to determine the age of a fossil.
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Very roughly 2 billion years ago.  But you should be aware of two points. \n\nThe first is that the date is a matter of considerable debate and it could easily be half a billion years either side of that.\n\nThe second is that the transition was extremely slow, starting with the addition of oxygen by inorganic processes and then taking a massive leap with the evolution of oxygen producing autotrophs.
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1. Because carbon-14 has a half-life of only 5,730 years.  So after 60,000 years there is not enough left to measure reliably.  That's why carbon dating is *not* used for fossils (despite what many people, including most creationists, think) ... there are dozens of other techniques used for dating fossils and rocks.\n\n2. Because it only works on things that were eating or breathing carbon ... i.e. things that were once alive.  (So it is useless for rocks, or asteroids, much less stars.)\n\n3. Because you actually need a sample of what you are dating ... so you could not use it to date things like distant stars or galaxies (the things that go back to the Big Bang).
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Scientists look for a great many things.\n\nScientists want to know what the Earth used to be like.  They look at fossils, among other things, to find out.\n\nPretty much every aspect of fossils is examined.  Given any on fossils, scientists will be trying to determine:\n\n* How the individual lived.\n* How it died.\n* What died with it.\n* What it says about the larger world.\n\nFor instance, scientists know that some Sauropod dinosaurs (ones like Brontosaurus) lived in herds because they frequently trampled on each other's tails.  Sauropod tails have large numbers of these minor injuries, suggesting such tail damage was common.\n\nA single fossil will be examined for bone damage to see what killed it.  Sometimes, they can identify the species of animal that attacked the the fossil.  They also look for traces of scavengers afterwards, and even decay processes!\n\nFossils of animal dung are examined to see what was being eaten.  These are called coprolites.\n\nFossils of "supersized" insects in the ancient past tell us that the oxygen in the atmosphere used to be much higher.  Today, an insect that large would suffocate.\n\nEvery aspect of a fossil is examined.  How big it was, how fast it grew (from growth lines), everything.\n\nIt's a detective story!  Come help us figure it all out!
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There are a lot of different dating techniques.  (The second link talks about some) Usually, when dating something, you don't just use one technique one one sample--you try to find a few different ways, and use them to build up a case for the age of something.\n\nSome dating systems are relative, in that they can only tell you which came first.  This is useful because it lets people assemble a chronology of things, even though it won't have absolute dates.  Once you have this chronology, you can use absolute dates to start finding approximate ages for things. For example, there's a distinctive layer of iridium in many rocks. If you find something below that layer, it's a good bet that it's older than the layer is.  Once you know that the layer was put down about 65 million years ago, you can start to narrow down the date of the things beneath it.\n\nRelative techinques are also useful as a test for the absolute techniques--if you know what order things happened in, you can use that to check that other techniques are giving sensible results.\n\nThere are also a lot of different absolute techniques--see the third link for a disscussion. Some, like counting tree rings, are very accurate, but only go back a few hundred or thousand years. Others, like carbon-14 dating, work on things that were once alive.  Still others, like Uranium-Thorium dating or archaeomagnetism, only work on certain kinds of rocks. Carbon-14 and U-T dating work by looking at how much radioactive materials in the sample have broken down, and archaeomagnetism works because the Earth's magnetic field has changed over the ages, leaving signs in some minerals.\n\nFinally, you can just look at the things that are near a sample.  So, if an archelogical dig contains a kind of pottery that you know was used 3000 years ago, that's a clue that the site is about that old.  If a layer of rock is full of fossils of animals that lived 300-200 million years ago, the rock was probably formed around then.
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People have been finding dinosaur fossils for hundreds of years, probably even thousands of years. There are references to "dragon" bones found in Wucheng, Sichuan, China (written by Chang Qu) over 2,000 years ago; these were probably dinosaur fossils.\n\nMuch later, in 1676, a huge thigh bone (femur) was found in England by Reverend Plot. It was thought that the bone belonged to a "giant," but was probably from a dinosaur. A report of this find was published by R. Brookes in 1763.\n\nThe first dinosaur to be described scientifically was Megalosaurus in 1824, by William Buckland a British fossil hunter and clergyman who discovered some Megalosaurus fossils in 1819 and named the reptile in 1824. It was the first dinosaur ever described scientifically and first theropod dinosaur discovered (this is all in hindsight, because the dinosaurs had not yet been recognized as a separate taxonomic group - the word dinosaur hadn't even been invented yet).
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The era you are asking about is Jurassic (it was between the Cretaceous and Triassic period). As for the fastest dinosaur in this era, if what Paleontologists have found is correct, I believe it was Compsognathus.
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Well you can date in-situ rocks relative to others by a few basic principles such as fossil evidence and sequence stratigraphy (if one rock is 'cut' by another then the it is older).\nIf you have an entire sequence of rocks right up to the present time the you could use deposition rates to calculate age but I wouldn't rely on it.\n\nTo calculate the age of a single sample of rock that is not in-situ I don't think is possible.  We use radioactivity because we know the rate at which it changes over time.  We understand the passing of time because things change.  If you were put to sleep in a dark room with no contact with the outside world then after about 1 week you would have no idea how much time had passed when you woke because you wouldn't have a point of reference.
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The earliest living organisms were single-celled. They were prokaryotes, probably bacteria or archaea. They lived 3.8 billion years ago in the Eoarchean Era, a subdivision of the Archean Era.
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Fossils (from Latin fossus, literally "having been dug up") are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. The totality of fossils and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils is called paleontology.\n\n \nFossil fish of the genus KnightiaFossilization is actually a rare occurrence because most components of formerly-living things tend to decompose relatively quickly following death. In order for an organism to be fossilized, the remains normally need to be covered by sediment as soon as possible. However there are exceptions to this, such as if an organism becomes frozen, desiccated, or comes to rest in an anoxic (oxygen-free) environment such as at the bottom of a lake. There are several different types of fossils and fossilization processes.\n\nFossils usually consist of traces of the remains of the organism itself. However, fossils may also consist of the marks left behind by the organism while it was alive, such as the footprint or feces of a dinosaur or reptile. These types of fossil are called trace fossils (or ichnofossils) as opposed to body fossils. Finally, past life leaves some markers that cannot be seen but can be detected in the form of chemical signals; these are known as chemical fossils or biomarkers.\n\nFossil sites with exceptional preservation are known as Lagerstätten. These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying decomposition. Lagerstätten span geological time from the Cambrian. Examples are the Cambrian Maotianshan shales and Burgess Shale, the Devonian Hunsrück Slates, the Jurassic Solnhofen limestone, and the Carboniferous Mazon Creek localities.\n\nThe oldest known structured fossils are most likely stromatolites. Now understood to be formed by the entrapment of sediment by mucous-like sheets of cyanobacteria[1], the oldest of these formations dates from 3.5 billion years ago. Even older deposits (3.8 billion years old) of heavy carbon that are indicative of even earlier life are currently proposed as the remains of the earliest known life on Earth.
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The Greeks and Romans may have found fossils, giving rise to their many ogre and griffin legends. There are references to "dragon" bones found in Wucheng, Sichuan, China (written by Chang Qu) over 2,000 years ago; these were probably dinosaur fossils. \n\nThe first dinosaur to be described scientifically was Megalosaurus. This genus was named in 1824, by William Buckland; Gideon Mantell (not Ferdinand August von Ritgen) assigned the scientific type species name, Megalosaurus bucklandii. Buckland (1784-1856) was a British fossil hunter and clergyman who discovered collected fossils. (Note: the first dinosaur found was Iguanodon, but it was named and described later than Megalodon.)