Best First wrote:so out of curiosity how do we know hos old dino's are?
Me Grimlock must know.
Most famous people are full of ****. Actuallu so are most people, including me most probably. Everyone talks crap at some point. Its more a question of intent and sincerity i think.
basically with out human interfearence soil and rock will cover land at a vaguely consistent rate. basically by seeing how many levels of rock and what type, and you can see at what point it was burried and how llong it must have taken the rocks to cover it. As most Dinosaurs bones consistently tell us the same period for each species we can get their time scales for when they lived.
As for carbon dating, which most people mistakenly believe tells us how old Dinosaurs here's how it works and why it can't be used for determining how old Dino's and the earth is, for the heck of it :
In my teachery way. Sorry if this seams over simplified as I'm so used to explaining this to children I can't seem to do it any other way :
Basically atoms are made of protons, neutrons and electrons. There are 108+ different types of atoms (referred to the different elements).
the defining characteristic of the properties of the atom is the Proton. If an atom has 1 proton it is hydrogen, if it has 2 it's helium etc. Carbon has 6 protons etc and as long as any atom has 6 protons it is Carbon.
However, the number of neutrons in an atom, other than making the atom lighter (If 1 is missing) or heavier (if more neutrons are present) doesn't appear to change what the element is. Carbon normally has 6 neutrons.
However in all living things there are a set of new carbon atoms with 2 extra neutrons.
These ones are often referred to carbon 14 (normal carbon is carbon 12 - 6 protons + 6 neutrons). C14 is generally made by cosmic energy Turing a proton in Nitrogen into a neutron (Nitrogen has 7 protons as 1 is turned to a neutron it has 1 less proton and becomes carbon).
Carbon 14 like all radioactive materials decays over time. By measuring the amount of carbon 14 in organic or Rocky material you can measure how long it has been in existence.
Over time the Carbon 14 gets less and less (The atomic decay will change the structure of the element into nitrogen and the decay is always consistent and not affected by any other factors.
Hence by measuring the half life (how long it takes for Carbon 14 to half in number) you can work out how old a carbon based material is by working out how long it took to get from the original proportion of Carbon 14 elements (because it is alwasy the same at the point of death) to the level it is at now.
The most common mistake of radioactive dating is that it is only accurate to thousands of years. It can't tell us how old the earth is and I not believe it can be used for Dinosaurs because they died over a millions years ago and the Carbon 14 decayed a looong time ago.
Hope all that interested somebody.....