I have been taught this as fact ever since I could speak, but recent conversations with, umm, “hard-core” Christians tell me that dinosaurs died out probably just 6 thousand years ago at the latest.
I immediately did some research and came up with various (in fact numerous) quotes and figures explaining how dinosaur fossils are found only in the mesozoic aged-rocks. What they don’t say, is how we know mesozoic aged rocks are 225 - 65 million years old.
So exactly how “certain” are scientists that dinosaurs died out 65 million years ago? Especially considering that I have been taught all this as fact in every text book and by every teacher that I have encountered.
Carbon dating is most commonly used to establish the date of ancient things. Fundamentalists point to the inexactness of such a procedure as a loophole. Without going into the specifics of the process (I’m sure some Madame Curie wannabe will take the time if it becomes necessary), suffice to say that a great deal that we think we know about radiation and particle physics would have to be inexcusably wrong for the carbon dating process’ margin of error to be on the magnitude of 400,000 times (200 million years vs 6000 years, plus and minus).
Actually, carbon-14 dating only works on specimens that are less than 50,000 years old, so it couldn’t be used to date anything from the extinction of the dinosaurs. There are, however, other radiometric dating techniques, like potassium-argon dating, with much longer timescales.
OK, first off the half-life of Carbon-14 is only a few thousand years, so it cannot be used to date things older than a hundred thousand years old.
However, there are other radioisotopes that decay at known rates that have much longer half-lives. One is Potassium, which decays into argon. You can tell how old rocks containing potassium are by the amount of argon trapped in the rock. Lots of argon means older rocks. And since we know the rate K turns to Ar, we know how old the rocks are, once we’ve made sure the rocks aren’t contaminated, are intact, are properly collected, etc, etc.
BUT, that is not why we think the dinosaurs lived a long time ago. The whole mesozoic, cretaceous, jurassic, etc time line was worked out long before anyone ever dreamed of radiometric dating. Even without radiometric dating, we knew dinosaurs lived before modern mammals, fish before reptiles, etc. And we knew that this took a long long time, probably millions of years because that was how long it would have taken to build up the sediments we saw.
What radioisotopes did was let us put hard dates on the geologic eras. Now we know the dinosaurs died out 65 million years ago because that is the age of the rocks at the cretaceous/tertiary boundary. Before that, we just knew that the KT boundary was very very old, millions of years old, but exactly how old no one knew.
Only idiots and liars believe that dinosaurs died out in Noah’s flood, because the Bible says that Noah took EVERY creature on earth with him in the Ark. The dinosaurs would have to have either died out before the flood, or after the flood, but it is impossible for them to have died DURING the flood, and only an atheist would believe otherwise.
I agree that you should check out http://www.talkorigins.org to find out some good info about determining the dates of fossils. Figuring out the age of fossils is a key point in the argument.
Your hard-core Christian (fundamentalist) friends believe the Bible’s literal word and by adding up all the “begats” since Adam & Eve, came up with an age of the universe of about 6,000 years. So, they then try to fit everything (when dinosaurs lived, etc.) into that timeframe regardless of the facts.
In addition to the “dating” techniques, there are several independent lines of scientific evidence that disprove the “young Earth” idea. Cosmology, astronomy, evolution, geology, etc. all indicate that the world and universe are vastly older than 6,000 years (more like 4.5 billion years for the Earth and 12-15 billion years for the universe).
Dinosaurs (at least the large ones, and not the smaller species that evolved into birds) are all fossilized in rocks that are older than about 65 million years ago. Above that sedimentary layer, no dinosaurs. Below that sedimentary layer, no human fossils (or anything resembling a homonid species). The rate of evolution happened to require billions of years to form dinosaurs from whatever lifeform came from abiogenesis. Millions more years were needed to evolve the small mammals of the dinosaur’s time into humans. Of course, fundamentalists say all species were created at the same time as stated in Genesis.