How do they date Fossils?

Answer 1

In practise, if you have a fossil and want to know how old it is, then 99.9% of the time the best way to figure it out is from the other fossils that are found around it.

The way it works is like this. Only a few sedimentary rocks are suitable for getting an 'absolute' age from, as in 2.55 million years old, 345.5 million years old etc. As said previously, these 'absolute ages' are determined from radiometric dating of certain minerals in the rocks (mainly using the decay of uranium-235 to lead-207 in minerals such as zircon, or the decay of potassium-40 to argon-40 in volcanic ash).

The ages of all the rest of the sedimentary rocks in the world have to be inferred by correlating to these known tie-points. And fossils are the best way to do this, since on average species only exist for around a million years or so, and new ones are always evolving (or appearing if you don't believe in evolution).

Where it gets complicated is species might have restricted geographic ranges, only lived in certain environments etc. But there are many paleontologists/geologists worldwide employed at figuring out which are the best fossil species or combination of species to use for every situation (like me). So in practise there are usually 'index species' which you look hard for to give you an approximate age, which lies somewhere between the ages of 2 'absolute' tie-points, somewhere else in the world.

That's if we need to put a 'date' on a fossil. Most of the time it's much better to say it belongs to a 'Zone' named after a particular fossil species, or a particular stage of geological time.

Hope that makes sense

Answer 2

Radiocarbon 14 dating is useless for all but the youngest of materials; after 8 half-lives, virtually all of a given radioactive isotope will be gone. C14 has a half life of 5730 years, give or take 40 years (reference 1). After more than 40,000 years, it will be present only in virtually undetectable quantities.

Other forms of radiometric dating may be used for rocks; there is a list of them on Wikipedia (reference 2).

However, age dating of rocks is more frequently a relative thing; it is important to know that one layer of rock is older than another. For these purposes, it is important to know what fossils are present; it also depends upon whether the sediments are aquatic or terrestrial. For example, in many aquatic sediments, we find fossils called conodonts (reference 3); because the creatures that made these fossils were found in oceans world-wide, we can say that a given type of conodont found at a given layer means that all rocks with this type of tooth is the same age. As conodonts evolved quickly and appeared as many different types, they may be used for relatively fine relative dating of sediments.

Other, larger fossils- such as ammonites, fish, etc.- may be used for relative dating. In this manner, someone who is working on a certain fossil bed can say that their fossils are, say, between 40 and 45 million years old, based on some research someone did on layers above and below what they're working on. Finer resolution is possible, but would require additional radiometric dating, as above.

Answer 3

The Earth is approximately 4.7 Billion years old and Fossils start appearing approximatley 3.8 billion years ago. The fossil dates come from the age of the rocks they are found encased in.

Answer 4

A process called Carbon-dating. As the years pass, the carbon in once live tissue is brokendown. Carbon has a half-life of about 6000 years, so determining the amount of carbon left in the fossils will tell you how old it is.

Answer 5

You obviously do not understand what you're talking about. attempt actual getting to understand the way radiometric courting is executed, exceptionally for geologic strata formerly posting questions like this. In different words, flow back to technology classification and attempt back, son. Edit: "you're saying innumberable isotypes will be used, yet I imagine that numerous of the topics i discussed with carbon courting also get up with them. If not why would carbon courting nevertheless be the most universal? and how can rocks be older than different rocks? the position did the recent, youthful rocks come from?" the reason human beings keep telling you that you fail at understanding what you're talking about is because you're making comments like this. Even some weeks at your community community college actual anthropology classification will sparkling up all of those questions, yet you at the on the spot are not attracted to that, are you? You look so a lot extra attracted to easily cherry-choosing even with testimony you'll locate that helps your concept and to hell with something else. properly, i'd hate to burst your bubble, yet this is not how technology works. In technology, you base your conclusions on evidence, not any incorrect way round.

Answer 6

fossils were alive sometime ago. They all had Carbon. One isotope of carbon is radioactive. It is evenly distributed in Nature. They know the half life of it and activity is measured by instruments roughly giving us how many are still there and still radioactive and thus age is calculated.

Answer 7

They call them up and ask them to meet for dinner and drinks. Naturally, they expect the fossils to pay, and generally the fossils will pay, depending on the level of competition for their time and attentions.

Answer 8

Carbon 14 half life
Strata dating

Answer 9

See, all the organic things are made of carbon,,,,,,,
carbon is basic element of all types of life exists on earth,,,,,,,
every organic matter contains C14 i.e. radioactive form of carbon,,,,,,
when organic things die,,,,,,,, its starts disintegrating,,,,,,,,,, and the amount of C14 starts decreasing,,,,,,, but it never finished,,,,,,,,,

the amount of C14 remained in fossils,,,,,,, decides the age of the fossils,,,,,, from which time it starts disintegrating,,,,,,

Answer 10

They look at their birth certificates..haw haw..

But really..there are many methods, such as carbon-dating. Also, they can pinpoint their basic age by determining the age of the rock layers in which they were found.