Why do you only have fossils of a fraction of the things that have existed on Earth?

Answer 1

There are very many reasons why some living things did not fossilise.

• natural processes will bio-degrade living things after their death.
• soft tissue does not usually fossilise.
• pre-historic predators and scavengers may have destroyed or scattered the potential fossil.
• modern predators or scavengers may have destroyed or scattered the potential fossil.
• geological changes may have obliterated fossils.

Answer 2

Many environments destroy fossils over time. Many environments are not suitable for fossil formation.

Answer 3

There are very many reasons why some living things did not fossilise.

• natural processes will bio-degrade living things after their death.
• soft tissue does not usually fossilise.
• pre-historic predators and scavengers may have destroyed or scattered the potential fossil.
• modern predators or scavengers may have destroyed or scattered the potential fossil.
• geological changes may have obliterated fossils.

Answer 4

First of all, over 99% of all species that HAVE existed are now extinct, so, even the staggering complexity of life that currently exists on Earth represents less than 1% of all lifeforms in history. A LOT of these were small, rare, or didn't make good fossils, or they existed so long ago that very few fossils remain in accessible places today, so our chances of finding them are extremely small.

Conditions had to be right at the time of the creatures death to preserve it. The best preserved specimens were found in ancient tar pits or river beds where mud was thick. Exposed carcasses would be consumed or eroded by the elements.

There are many life forms that don't leave very good fossils. Fossilized bone lasts because minerals fill the gaps in the bone over time, slowly replacing what used to be bone with rock, as mineral rich water seeps in and dries. The other fossils we find are mostly imprints left in sedimentary rock.

Bone is a recent advancement, so there were many creatures which did not leave bone behind, so we will only find their fossils if they happened to die in a place where minerals were being deposited to form sedimentary rock in which they became encased. Like shale, which forms layers that can be seperated to find imprints of trapped organisms. This is how we find most plant fossils.

Some of these formations are exposed, or carved out by water (like the Grand Canyon) so they become good spots for fossils to be found, and thus, we learn a lot about the organisms that are found in these particular formations, but think of all the un-exposed sedimentary rock formations which contain the remains of completely undiscovered species.

The other major reason is that we only dig a small handful of spots; we can't very well dig into the ground everywhere as it would disturb the microbial soil community structure that supports the plant life that we rely on. So going around uncovering all of the ancient organisms would have negative impacts that far outweigh the benefits of discovering these organisms.

We find fossils during excavations for other purposes, like the extraction of Natural Resources like ore, minerals, or gas; though these processes can often destroy fossils unintentionally. Fracking, for instance, could uncover fossils in shale, but the hydro fracturing of the shale can destroy many of these fossils.

A lot of land used to be exposed when sea levels were lower, so many fossils of coastal organisms are buried in what is now the sea floor, which is, of course, very hard to dig for fossils in. With sea levels still on the rise, we have little chance of discovering many of these ancient coastal creatures.

Finally, some earth at plate boundaries gets pushed down and melts back into the magma, so there are some places where organisms did live, but we will never see their remains because they have been melted and re-incorporated into the planet.

Basically, the chances of finding the remains of an organism that didn't live in a place that later became sedimentary rock are very slim, and if an organism wasn't particularly abundant in the first place, there is just an extremely small chance of us actually encountering it's preserved remains in-tact.

Answer 5

Not all things can be fossilised. Most soft tissue will leave no traces. In many cases, predators and scavengers will destroy all remnants or scatter the fragments so that there is little evidence to link these back together. Natural decay will also play a big role in the process.

Answer 6

There are several reasons.

• soft tissue does not normally fossilise so fossils of animals without bones or scales are rare.
• fossils are based on organic material and, in general, that is bio-degradable. The potential fossil must be in rather special circumstances immediately after its death for its remains to fossilise.
• contemporary carnivores and scavengers may have dispersed the potential fossil before it could form.
• future carnivores and scavengers could disperse the fossil during or after it formation, but before it is found by people.
• natural phenomena such as erosion, floods and earthquakes - even on very localised scales - can destroy fossils.
• fossils take a very long time to form so there are no fossils of animals from the last century!

Answer 7

Many organisms live only in rainforests.

Answer 8

Many environments destroyed fossils over time