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Are All Dinosaur Bones Fossils? [Surprising] Reasons Why They Aren’t

We have all seen dinosaur bones in museums or learned about excavating fossils in science class. Dinosaur fossils are the most important prehistoric evidence that we have to look at. When discussing dinosaur remains, we usually refer to the bones as fossils. This is because every single dinosaur bone has, in fact, been fossilized. But these terms are not actually interchangeable. 

Are All Dinosaur Bones Fossils?

Are All Dinosaur Bones Fossils?

So, are all dinosaur bones fossils? No, not all dinosaur bones are fossils. Fossils are the remains or traces of ancient organisms that have undergone a process of mineralization. While many dinosaur bones have become fossils over millions of years, some have not undergone this process and are instead preserved as mummified remains.

If you’re as puzzled as I was when I realized this, I’m glad that I get to explain it all to you here. Understanding dinosaur fossils and what they mean for us scientifically is amazing and can possibly give you a greater love for the subject.

The captivating field of Paleontology has unearthed the mysteries of Dinosaurs – extinct giants of the Jurassic Period and Cretaceous Period of Earth’s past. These creatures, through their Bones, give us tantalizing glimpses of Prehistoric Times. Largely preserved as Fossils, these Bones have endured the relentless march of Geological Time.

The transformation of Dinosaur Bones to Fossils is an intriguing journey that entails their immersion in Sediment and eventual replacement by Minerals, found in aquatic environments where Sedimentary Rocks abound. Consequently, these Biological Remains metamorphose into Fossils – relics of our Ancient natural history.

Two illustrious representatives of this bygone era, the T-Rex (Tyrannosaurus Rex) and Triceratops, offer invaluable Fossils that shed light on Evolution. However, not all Dinosaur Bones are Fossils. Paleontology, aided by the allied discipline of Archeology, meticulously discriminates between fossilized and non-fossilized bones. While Dinosaur Bones frequently become Fossils, not all tread the path to fossilization.

Before we can get into some of the more specific questions to be answered, here we need to have a general understanding of fossils. Being able to explain how dinosaur bones can become fossils gives you a knowledge base that will help you understand any deeper concepts that you might come across while looking into the existence of dinosaurs. So, let’s begin with figuring out what a fossil really is.

What is a Fossil?

A fossil is any fossilized remnant of a life form from at least 10,000 years ago. This includes both animal and plant remnants. Fossilization at all is incredibly rare and it is even rarer for entire organisms to fossilize.

Many times, fossils come in the form of individual teeth, bones, or shells. These are referred to as body fossils. Softer parts of the body, like organs, skin, and muscles, cannot fossilize. Due to fossilization, these bones aren’t actually bones at all. They have been turned to stone.

Sometimes a fossil isn’t a remnant of a body part. Many fossils are just impressions that an organism made on the sediment, leaving behind an outline. These are called trace fossils. Trace fossils are not actual body parts, instead just showing effects of a plant or animal on the environment. Some examples of this are fossilized footprints or prints of plants.

Plants cannot really fossilize themselves, so plant fossils usually come in the form of what are more specifically called mold fossils. Mold fossils are the mirrored print of a plant that was being pressed into the sediment. After the plant deteriorates, the print is still there to show the appearance and size of the plant.

Fossil Types

Fossils come in all different sizes. Macrofossils are very large, like trees and massive predators. When you think of a Tyrannosaurus Rex skull, this is a macrofossil.

Microfossils can only be viewed under a microscope are things like prehistoric bacteria. While most fossils are stone, they can also be made of amber.

Amber is a type of fossilized resin that is made of sap from prehistoric trees. This amber can contain insects like flies and mosquitoes from millions of years ago.


Fossilized bone is, as we’ve figured out, not actually bone. However, there are some very rare cases in which bits of actual dinosaur parts have been found within the fossilized bone.

These parts included traces of blood vessels and tissue. Though DNA would deteriorate far before we could discover it, different proteins here can give researchers even more insight into the lives of these creatures.

Now that you know what a fossil is, you may be wondering how fossilization even occurs. Fossilization is a very specific and complicated process. For a carcass or plant to fossilize, the body must be buried, virtually untouched. The burial must be under sand, silt, or mud, as these can eventually turn into sedimentary rock.

Sedimentary rock is a type of rock formed by the combination of fragments from various rocks or remnants of plants and animals. Sedimentary rock is created by these fragments combining while being moved from place to place in the form of sediment. Sediment moves via erosion by water, wind, or ice.

Where Can Fossils Be Found?

In the case of having been moved by water, sedimentary rock can frequently be found at the bottom of deltas. Fossils are more prominently moved by wind. This means that they will be found in places with little vegetation. The places where most of these fossils have been found are known as badlands.

Badlands are geographical areas made almost exclusively of eroded rock. They are believed to have been formed by floods which brought mass amounts of sediment into the area, destroying any life and making the ground uninhabitable for plants. This created the perfect environmental situation for the creation of fossils.

There are badlands located all around the world, but there are plenty just within the U.S. Badlands can be found in states like Utah, Arizona, Oregon, Wyoming and, most famously, South Dakota. The Badlands National Park in SD even includes a Fossil Exhibit Trail where fossils discovered there can be viewed.

Other Kinds of Fossils

So, if fossils aren’t just dinosaur bones, then what else can they be? Well, we already talked about the trace fossils that plants can leave behind and microfossils of bacteria and other single-celled organisms. Different kinds of egg fossils are also quite common.

Egg fossils are more easily found than full skeletons of creatures. This is because it is very rare for a single egg to have been fossilized in a location without the rest of the nest. These eggs can also be found in large breeding grounds, meaning that there are dozens of eggs in one area.

It is equally as important to note that dinosaurs aren’t the only prehistoric land creatures that we have found fossils of. Remnants of ancient mammals, like saber-toothed tigers and cave bears, have also been found.

Teeth and jaws of the Mosasaurus, Megalodon, and Livyatan are in the fossilized bones of whales under ocean beds. Even fossils of our ancestors, like Homo Erectus, have been found. So, it’s clear that fossils are not limited to dinosaurs.

Why Do We Only Talk About Dinosaur Fossils?

After realizing how expansive the diversity is in fossils records, it’s easy to wonder why people associate fossils so strongly with dinosaur bones. While we can give some of that credit to the Dinosaur boom post 1993’s Jurassic Park, the film is not the only reason.

All fossils are important and should be studied, of course, but as far as fossils go, dinosaurs might just trump them all in significance.

There are plenty of extinct species of mammals from these prehistoric periods that we have been able to study, but they have very clear lineage to current species. Examples could be the wooly mammoth, who we can clearly link to modern-day elephants.

Or, the saber-toothed tiger, who we can put very easily within the big cat family. Predatory mammals are a problem that humans are still facing, so they don’t feel very foreign. Dinosaurs, however, are a vastly different story.

The Impact of Dinosaurs

Just as we are the dominant species now, so were the dinosaurs for around 135 million years. Understanding dinosaurs is understanding a group of creatures that we do not have clear, direct descendants to in the modern age. It took ages for us to even theorize that birds were descended from these seemingly-reptilian creatures.

Dinosaurs are also the key to looking into mass extinction and the effects that can have on an ecosystem. We have no evidence as strong as that of the dinosaurs to have reason to study anything else with such vigor.

It’s also important to remember that dinosaur fossils themselves include a vast diversity. Hundreds of species have already been determined and are being studied, so it makes sense that an entire career field is dedicated to it.

Knowing the Unknown

Most of all, though, it is the fascination with a world unknown. Because humans and dinosaurs never crossed paths in existence, so many questions will seemingly always go unanswered. Their interesting bone structure and unclear lineage leave us all curious about how they would move, communicate, and sound.

So, the popularity of dinosaurs can really be rooted in that curiosity. It is why children surround themselves with dinosaur toys and books and why we love seeing them represented (albeit inaccurately) on the big screen. So, it makes sense that when discussing fossils, dinosaurs are the first thing we think about.

With all of that knowledge covered, I hope that you have a grasp on how fossilization and dinosaur remains interact. While all dinosaur bones are fossils, you understand now that not all fossils have to be the remains of dinosaurs.

The Importance of Fossilization

Fossilization is one of the most perfect natural preservation processes to exist and is basically a miracle in and of itself.

We can learn so much about dinosaurs and the past overall from looking at fossils critically and making hypotheses about the kind of world we never got to live in.

Learning about dinosaur fossils can give us a much deeper appreciation for the hard work that goes into studying these creatures. I hope that this article assisted in giving you that appreciation and that this knowledge can help you understand dinosaurs overall.