How long does fossilisation take?

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What is the minimum amount of time it takes to fossilise something? (asked by Nick)


Fossils are defined as the remains or traces of organisms that died more than 10,000 years ago, therefore, by definition the minimum time it takes to make a fossil is 10,000 years. But, that is just an arbitrary line in the sand – it means very little in terms of the fossilisation process.

The actual process of fossilisation is highly variable. Really, it is a catch-all term for all processes which yield traces or remains of dead organisms. Assuming we’re talking about preserved remains and not trace fossils, the process of fossilisation that we are usually dealing with is permineralisation, whereby minerals are incorporated into the structure of the preserved tissue (bone, flesh, feathers, etc). During this process, liquids and gases from the living organism are slowly replaced by mineral-rich water. Overtime, the minerals fill the empty spaces and we are left with the familiar structure of a fossil – a living organism that appears to have been turned to stone. Other forms of fossilisation can involve replacement of the original mineral content of the organism with different minerals, or recrystalisation of the same minerals into different forms.

Trace fossils, on the other hand, form when the remains of the organism decay, leaving an empty space or cast of the original organism. Alternatively, they can be formed by compression which can leave a compressed fossil of the original organism, or a trace fossil if the remains are later destroyed.

One thing all types of fossilisation share in common is that they require the dead organism to be trapped underneath layers of sediment. This is what makes the fossilisation such a rare event – if the organism is left exposed after death it will usually be destroyed by decay and scavenging before it has a chance to be fossilised. But, under the right conditions, fossilisation can occur relatively quickly – in the ballpark of hundreds or thousands of years.

Let’s consider just permineralisation – what most of us think of when we think about fossilisation. Permineralisation requires a good availability of minerals such as sulphur, iron, carbon and silica, in the water or sediments around the fossil. The more minerals available, the more rapidly fossilisation can occur, assuming other conditions are optimal.

The speed at which this occurs will also depend strongly on the size of the organism – tiny organisms, eggs or embryos can actually fossilise really quite quickly. Perhaps in a matter of weeks or months. Eggs may be particularly good for rapid natural fossilisation, too, as in many marine species they show adaptations to slow the rate of decay (a good idea if your method of fertilisation involves floating around in the sea for an extended period of time!) which offers a larger window of opportunity for fossilisation. In the laboratory, paleontologists have been able to fossilise lobster and shrimp eggs in just 2 – 8 weeks!

Similarly, researchers in Washington have developed a method that can speed up the process of wood petrification (which begins with permineralisation) in the lab, producing chemically petrified wood in just a matter of days!

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31 comments on “How long does fossilisation take?

  1. There was a fossilized cigarette lighter found in a
    Drained lake with a date etched in it. Why then would
    It be said that it takes 10,000 years for a fossil to be
    Created?????? I think this proves it’s way off

    • Hi Bev,

      Please can you back this claim up with some evidence? Do you have a link to a news article about this remarkable discovery? Also, if you read the long answer you’ll see that fossilisation can take anywhere from a few days to tens of thousands of years, depending on the conditions. So I’d say this fossilised lighter must have experienced great temperature and pressure over a short period of time.

      Thanks for reading!

      • Was the lighter made of metal? Fossilisation as I know it is the replacement of soft tissue cells with mineral deposits. Metal will not fossilise in this way. Plastic certainly won’t.

    • What was the said lighter made of, most are not made of organic material but usually metal or plastic and neither one of those will petrify

  2. The other day i found a very large bird egg in the very final
    Like the last of the last an i looked at it today and it turnd to stone
    And i was able to identify a bird shaped creature in the middle of
    The egg. Ive been trying to get into contact to some one that
    Is able to identify what species of bird and carbon date it.

  3. Actually fossilization has happened way back when it flooded 40 days and 40 nights during Noah’s times. Fossilization happened one time big time. Why? It’s because if fossilization will happen in 10,000 years, it actually won’t since decomposition will occur not decomposition. I’m sorry, but with all your respect, this article is ultimately WRONG; it goes against the Bible, God’s Word. The Bible is the only true evidence that everything happened that time.

    • umm and thats why GOD is fake, made up, ideological just like all religions…. root of all evil really, i feel its a big part why humans are gonna be stuck in an evolution slump…. because people are seriously so naive believing in such ridiculous fairy tales …. i grew out of santa when i was fairly young…….. humans have to figure out consciousness really soon ….. or humans very very very short experiment which we call life will not last much longer…. and you should probably keep your IDEOLOGIES OUT OF SCIENCE ……. 46-2 …. CHROMOSOMES… CONSCIOUSNESS is key… vatican pedophiles know how the pyramids were build… i will telepathically in-pregnant your wife…like mother mary…

      • Stalin , Pol Pot , Mao were evil and caused millions to die . They were all atheist . If there is no God , then we are all cactus very soon. I am glad to have religious faith that gives me peace of mind and ethical guidelines . A Christian is one who follows Christ not one who sais they are Christian . Pedophiles hide in churches . They are NOT Christian !

        • Hitler: christian. Trump: christian. Putin: Russian Orthodox christian. Joseph kony: christian. KKK: christian. James Knight: christian. Erick Rudolph: christian. Shelly Shannon: christian. David Koresh: christian. James Jones; christian. Anders Behring Breivik: christian. Westboro bapist church: take a wild guess.

          All mass murders and terrorists.

          If you need an all-powerful being to give you morality, and couldn’t be given it by looking in the face of an innocent child, or do it on your own: you are not a good person in the first place.

          Also: did you fail 3rd grade grammar, or do you have some neurodegenerate disease that makes your writing sound like your thoughts were conceived by a moldy potato with a tinfoil hat?

      • Wow,thank you .
        Now I understand my afterlife experience completely :)!
        I was always told it was the drugs they gave me that “created” the experience of me standing before Jesus .
        The problem with that was I had TBI and they did not give me any drugs until it was safe to administer them ;).
        Why would you leave heaven to come here at risk of your Immortal soul ?
        I would not ,but as an Immortal I would come here to experience Death ;). Something an Immortal can not do ,except here ;).
        Try the King James Bible john 3:13 . Kinda puts things in perspective or knot ;).

    • To Zyroon:
      You do both religion and science a great disservice by conflating the two. To expect God to hand you down from heaven (whatever you may think that is) a vaccine for the covid-19 virus while you do nothing but sit and pray is patently absurd. To expect science to comfort you when your child gets run over by a car is equally misplaced.
      Peer-reviewed and replicable scientific findings present facts upon which knowledge about the world can be based, trusted and built upon. The Bible does not do this nor was it ever meant to; parables are not facts but stories. No one knows when the first Judaic laws came into existence, long before writing, that led to the first five books of what is now called the Bible. Certainly much much more than 5,000 years ago and long before what we know as “science”. Religion is not biology, math, chemistry, medicine, economics, anthropology, nor any of the other vast number of subjects studied in universities around the world. Mircea Eliade makes the distinction between the “sacred” and the “profane”, and that is what I would suggest you consider doing, because opposing religion to science is impossible, is unworkable, and only leads to unnecessary and misplaced arguments and unhelpful conflict.
      Besides, what good is the Bible, for instance, if you don’t read it cover to cover several times and ingest its wisdom? Doesn’t it say something about rendering unto God what is God’s and unto Caesar what is Caesar’s? In other words, understand what belongs to science (the profane) and what belongs to God (the sacred) and don’t expect one to stand in for the other. And equally, respect what each has to offer. Paleontology is a very sophisticated science and has much to teach us about the past (and our past). The Bible, on the other hand, is made up of ancient stories that served at the time they were codified, after being orally handed down for centuries, as rules (laws) that governed social behavior and rendered human groups cohesive. The idea of a Supreme Being has from prehistory provided a pinnacle of right behavior without which society would have no measure. These laws were never scientific, that is they were never meant to form, test and explain ideas about the physical world.

  4. I have personally seen, on the south ran Gabriel river, in Texas, dinosaur footprints from millions of years ago, next to wagon trails made by early settlers to central Texas in the 1800s that were fully fossilized, hard as a rock limestone… it doesn’t take long for mud to turn into rock.

    There are other places where people have found human footprints next to dinosaurs footprints, and people argue profusely that they were made at the same time because “it takes millions of years to make a fossil”… whereas it was likely that some native Americans were walking a river bed looking at the dinosaur footprints wondering what type of creature was so heavy that it could crush rock beneath it’s feet, and wondered if it would attack them in their sleep… then their muddy prints turned to stone a year later…

    To say “a fossil is anything over 10,000 years therefore it takes 10,000 years to make a fossil” is not only true but inaccurate. That is like saying “the definition of a cake is anything over 10,000 years old therefore it takes 10,000 years to make a cake… well the cake took 3 hours, but it wasnt a cake by definition until someone found it in a cave somewhere…

    This is very much “the glove doesn’t fit” lawyer speak.

      • Pearler,

        May I ask what you did with you human. I think that I found a fossilized or peterified human skull, Its small
        but definitely a skull. It has black sand in its eyes and nose area. I dont know where to take him or what to
        do with him.

    • Mb, Hmm. I used to live within walking distance of those tracks in the South San Gabriel river, and had no problem understanding that the dino prints were made when the limestone was still made of mud, however, the wagon trails were ruts ground into the limestone river bottom where they crossed repeatedly. If the ruts were made in fresh mud that later fossilized, there would be human footprints along side them don’t you think?

    • Can you clarify that a little, dinosaur footprints in the rock which was once mud, but men made footprints in the mud next to the dinosaurs rock footprint.
      So were they rock and mud together or one was rock and the other mud or both mud or both rock, did the rock return to mud or the mud turn into rock at different times or the same time.
      Quit a confusing question but not as confusing as the statement.

    • If you had read the article, it did mention depending on the circumstances, fossilisation can occur anytime within weeks even. What you stated to oppose here is literally just the first paragraph of the article.

  5. Does anyone know whom to talk to about finds. I’ve discovered a small fossilzed skull still in it’s process. One side of it is still exposed and teeth can be seen, on the other side it’s rock solid. I was looking for quartz in the San Luis Obispo area, and I’m hoping to learn more. But it’s no bigger than my hand.
    Please email me at

  6. Thank you very much for this article. I had been trying to understand the well-known fossil named Lucy what is actually a fossil or the actual bones of an organism. I now understand that fossils can form more quickly then I previously assumed.

  7. Fossilization can take anywhere from hundreds of years to several thousand of years. The thing is, DNA from teeth? Dental pulp provides DNA and it has a half life of 521 years. I don’t see how DNA could from teeth after 10,000 years could provide anything

  8. Hi
    I have found a skull cap, complete with left Supraobital Foramen intact, the right one is damaged and the cap is stone
    I have pictures if anyone would like to see

  9. I found a what iam calling a fossil, based on definition. It’s a small part of what looks to be of shark, maybe a small one or of some kind of fish. I would like for you to see it an even feel it. Ism very sceptical because on my readings of smaller things have been recorded. If do please take a few minutes with m ed on this

  10. Before you comment, please read the entire article…
    More than half of these commentors seem to have not read
    Anything more then the first cover line of the article
    10,000 years was just the headline, they also noted that
    Fossilization under the correct circumstances could
    Take 2 weeks for select organisms.
    Also, why bring religious views into a scientific article?
    Why cant religion and science work hand in hand??
    Why do they have to battle each other?? Their are so many
    Scientists that are religous people, it doesnt have to be
    A war of ideology. Whose to say a god didnt put all this
    Stuff into motion?

  11. This answer is completely ridiculous and utterly false. Fossils are not the “remains” of dead organisms. They are stone. Minerals are exchanged with biological material, and the minerals are in the shape/form of the organism as an image. Moreover, the duration of this mineral exchange is not equivalent to the age. The fossilization happens much quicker. How do I know? Because an organism cannot be fossilized (turned to stone) after it has ceased to exist, and biological material generally decays within weeks, often within days. Even the bones will usually decay in less than 15 years unless protected from oxygen and microbes in some way. After that, thermodynamic decay happens in less than a few thousand years. If fossilization does not happen while the organism still exists, it does not happen at all. Fossilization happens quickly. It simply must. Your answer is ignorant.

    • Perhaps you should re-read the answer, taking note of what it actually says, before dismissing it. You seem to be confusing fossils formed by permineralisation and trace fossils.

  12. Dear Ms Asher,
    I am writing to seek your expert views on petrifaction of human bones and tree stumps and
    and branches. I live close to Taxila the ancient capital of Gandhara Civilisation. A short
    distance from archeological sites there is multi mouthed cave. Nearby flows a parental
    natural spring on which a pond is constructed. The construction of the pond from the material
    used, does not appear recent.
    The cave walls are full of fossilised human bones. The hill with the caves as well as other hills
    around it are made of sandstone and lime.
    My question: 1. How can one determine age of the petrified bones in the caves.
    2. What could be the cause of such a large collection of “ancient” bones.
    Should my query interest you, I would be glad to share further information.
    Zubair Osmani

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