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Fossil vs. Bones:  What’s the difference? 

I remember the joy I had to go fossil hunting as a child and finding wonderful treasures.  I also remember the absolute disappointment I had at finding out they were, in fact, not fossils but bones.  Although I never discovered any real fossils, I had to learn the difference between a bone and a fossil…  

Bones are the part of the body that forms the skeletal system; they are also often the last part of the body to decompose, which takes many years.  A fossil, in contrast, is the solidified and preserved parts of prehistoric organisms, animals and plants, which deliver vital information about the world they lived in.  

There is an obvious difference between bones and fossils, but they are both equally important to help us understand the world we live in now and the world that existed before we did.  

Anthropologists can determine many things from the bones they discover, including:

  • how the animal or human lived and died
  • the age and gender
  • the age of the bones
  • the possible environment the animal or human lived in.   

Paleontology is useful in the study of extinct plants and animals, and this study gives us many insights into:

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  • the evolution of species
  • climate changes
  • ancient cultures. 

What do Skeletal Remains Tell Us?  

The skeletal remains of a human are often examined because of one of two reasons.

  • Either it is the skeletal remains of a person who died many years ago and useful information about the time can be discovered
  • or it is the skeletal remains of someone who died more recently, and the cause of death needs to be discovered. 

In both cases, an anthropologist can gather useful information by simply examining the deceased person’s bones. Here are some of the main things that they look for during examination… 

  • Gender: Gender is the first determination that can be made, and it is done by examining either the pelvis or the skull.  The pelvis of a female provides a wider opening because of its necessity during childbirth.  The skull of a male provides more robust features with pronounced brows and a square lower jaw.  
  • Age of death:  The age determination relies mostly on the size of the bones when it comes to infants, children, and adolescents. For young children, the teeth can be a great indicator as to the age of the child, depending on the development or eruption of the teeth.  

In ancient adult skeletal remains, the teeth can indicate a possible age depending on how the teeth are worn down or how many teeth are present.  

If recent skeletal remains are discovered, dental records can be used to determine the age and the identity of the person.  

  • Race and origin:  The race of skeletal remains can be determined by using the skull’s measurements and the postcranial skeleton.  Anthropologists look at the shape of the jaw, the orbital region, and the teeth.  

The origin of the remains can be determined by analyzing the bone structure and taking into account where the remains were found.  

  • Trauma: Three categories of trauma can be discovered, which include:  antemortem, perimortem, and postmortem.  

Antemortem trauma is the injuries that took place while the person or animal was still alive.  This can help us understand the kind of life that the person lived.  For example it can indicate that the person has had a bone broken several years before death.   

Perimortem means shortly before death. These traumas were caused to the bone shortly before death, and it is often the evidence needed to discover the cause of death.     

Postmortem injuries are injuries that occurred after death, and they can give some indication of the time that passed and the events that occurred since the death.  

  • Time of death: The time of death is the hardest to determine, and it is sometimes done by examining the area around the skeletal remains, the postmortem injuries, the insect activity, and the cause of death.  

What Do Fossils Tell Us?

Fossils help give us information about species that lived long ago, and what their environment was like

Fossils tell us everything we know about the species because fossils are prehistoric animals and plants that lived long before record keeping.  The following can be discovered when examining fossils…  

  • Evidence of evolution:  Evolution happens slowly and over a long period, making it difficult to examine when one species evolved into another.  We have, however, made some discoveries into the evolution of amphibious creatures developing legs and becoming the first species to walk on land.  Other discoveries have led scientists to understand how dramatic climate change led some animals to evolve rapidly to adapt to the new environment. In contrast, other species became extinct in the same environment.  

  • Changes in climate and the environment:  The discovery of fossils in ice gave scientists information about the theory of a comet hitting the earth, which changed the climate so drastically that it led to the ice age.  Many species became extinct at this time.  This information was also determined by the age of the fossils and the soil in which it was found.  

  • Ancient cultures:  The fossilized remains of humans, plants, and animals can give us vital insight into how ancient civilizations lived.  The plants and animal fossils found near these civilizations give us some clues about what these people ate and how they lived.  Fossil layers found near these civilizations can also consist of artifacts and tools used by them.  

  • Biostratigraphic correlation: Geologists will match layers of rock found in one place to the layers of rock found in another place to determine the environment in which the fossils discovered there lived.  

  • Oil:  Fossil fuels get their name because the organic remains of prehistoric organisms form them.  By examining the type of prehistoric organisms found in a certain area, industries can determine where to dig oil wells when looking for gas or oil.  

  • The recording of fossils:  Recording fossil finds gave us insightful details about the past and life history.   

We often think of dinosaurs when we think about fossils, but the truth is that there are many types of fossils, each giving valuable information to us.  The type of fossil also gives us insight into the condition in which fossilization happened.  

What are the Different Types of Fossils?  

  • Body fossils:  These fossils are created when prehistoric organisms are trapped in tree sap; these organisms are embalmed after the tree sap hardens and becomes amber.  Organisms like these are embalmed with organic material, which disintegrates after death and leaves behind a hard shell or bones.  

  • Molds and casts:  These fossils are also body fossils because they leave an imprint of the animal behind.  Molds can be both internal and external.  From an animal with a shell, we can find an internal mold when sediment enters between the shell and the body, forming a rock imprint of the shell’s inside.  An external mold can be formed from the same animal when the sediment moves over the shell, creating the mold of the shell on the outside.  A cast is the replica of a mold, which is formed when the fossil shifts.  

  • Permineralization and petrification fossils:  Permineralization is the process in which plant or animal remains are saturated by groundwater, and some of the organism’s organic materials dissolve, leaving behind minerals.  The fossil will form its original shape, but the structure will be heavier.  Petrification happens when a fossil is formed, and the organic material is completely replaced by minerals and then turned to stone.  Woodturning to coal is an example of this.  

  • Trace fossils:  The process in which footprints, tracks, and trails are hardened and fossilized is known as trace fossils.  These fossils are very useful in determining how animals behaved and moved around.  There are often several imprints found together which suggests that they lived in groups.  Other imprints of the animals can also be found, like the imprint of a tail.  

  • Coprolites:  These fossils are fossilized fesses and can give a plentiful amount of information about the organisms.  It can give us an indication of where these organisms lived and what they ate.  They are most commonly found as coming from sea creatures with pieces of shells and bones in them.  They are created by cast and mold or petrification.  

The type of fossil depends greatly on the conditions in the environment and how the animal or organism was buried or died.  The process of fossilization contributes to the information that scientists gather to create the story of the past.  

For more detailed information on the the different types of fossils, check out my article, “9 Different Types of Fossils

How is a Fossil Formed?

Fossils can be formed in different ways

Fossils can be formed in five ways:  

  • Permineralization:  This chemical process takes place when minerals that are dissolved are carried away by groundwater.  These minerals are absorbed into the cellular spaces of plants and animals.  Crystallization of the minerals takes place and produces rocks in the shape of a plant or animal.  Permineralization is commonly found in the fossilization of bones, shells, teeth, and wood.  

  • Amber preserved:  This happens when an organism is trapped in tree sap that hardens into amber when buried underground.  Insects and pollen are examples of this type of fossilization.  

  • Natural casts are mostly found in marine invertebrates and occur when remains are washed away by flowing water.  Minerals fill up the spaces left behind and create an imprint of the original mold.

  • Preserved remains:  This is a very rare form of fossilization, and it is also the most valuable kind.  It happens when entire organisms get trapped in ice or volcanic ash.  Most of the remains are intact, including some skin, organs, hair, and muscle.  Examples of these fossils include mammoths.

  • Trace fossils:  These fossils are simply records of the organism.  They include footprints, nests, and imprints of plants.  

It takes thousands of years for a fossil to become a fossil, but the process of a body becoming nothing more than bones can happen in a month, depending on the environment’s conditions. The stage of decomposition in which a body is can give a timeline of when the death occurred, which is important to the people examining the body.  

How Does a Body Become Skeletal Remains?  

Skeletalization takes place a long time after the death of an animal or human. It is a natural process, and it happens to all dead bodies.  

The decomposition rate depends on the environment in which the body is and whether or not the body is buried.  Factor such as the animal and insect live plays a major role in the decomposition of animals and humans.  A dead body also influences insect activity, and currier birds and scavengers will also be drawn to the smell of decomposition.  

In the example, we will be studying the decomposition of a body that is not buried in a moderate climate.  

  • 3 Hours postmortem:  Rigor mortis sets in because of the stiffening of the muscles
  • 24- 72 Hours postmortem:  During this period, the rigor mortis subsides as the internal organs begin to decompose.  The decomposition of the internal organs occurs because a lack of oxygen kills the cells in the body.  This is also the period in which the body begins to emit unpleasant odors.  
  • 3-5 Days postmortem:  The microbes that make up the human immune system travels to the liver and gallbladder, where it breaks down the tissue, which in turn allows the bile within these organs to flood into the cavity of the body.  The bile will turn the body a greenish color.  
  • 8-10 Days postmortem:  The blood in the body starts to decompose, and the body will turn from green to red while gases accumulate.  
  • 2+ Weeks postmortem:  The teeth and nails will start to fall out as the tissues that keep them attached to the body decomposes and deteriorates.  
  • 1+ Month postmortem:   During this period, the blood vessels and the rest of the body cells deteriorated, and the corpse liquefy.  The bile and liquefied body tissue will even deteriorate the clothes on the body.  Often the only thing that is left is Nylon material, as this disintegrates over a longer time.  

Skeletalization takes place after this period, and it can start to happen any time after a month, depending on the environmental conditions.  The skeleton will not disintegrate for a long time because a coat of collagen covering the bone will make it difficult for the microbes to gain access to it. Bones will last even longer in a dry environment because the absence of water makes it impossible for microbes to survive.  

When bones disintegrate, they become dust. however, it takes a very long time on land.  If a body is in the water, the process can happen much faster due to the fungi and bacteria that will break down the protective layer on the bones.  


Fossils are the preserved remains of prehistoric animals, organisms, and plants, while bones are the skeletal remains of humans or animals. Both fossils and bones give us vital information that helps us understand the world in which the animal, human organism, or plant lived.  

Skeletal remains of people that lived long ago help anthropologist to discover how these civilizations functioned. Skeletal remains of people that had passed away more recently give scientists information about how the person died or even who the person was. This information can help in murder investigations or the identification of missing persons.  

Fossils give us information about prehistoric civilizations, animals, organisms, and plant life.  It also helps scientists map out a timeline of where life started on earth, how evolution took place and how certain animals, organisms, and plants became extinct.  

Fossils are formed in five different ways, and each type of fossil gives us a unique understanding of the prehistoric time they lived.  Trace fossils also give us information about how an animal moved and whether or not it lived in groups.  

How a body decomposes depends upon the environment, the animal and insect activity, and whether the body is buried or not.  The timeline is also dependent on these factors. 

For more information about fossils, check out my article, “9 Different Types of Fossils”