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How Deep Are Dinosaur Fossils Found? The Surprising Depths

When paleontologists recover dinosaur fossils, it’s usually with tools such as a brush, a chisel, a knife, and a probe. You know that fossils aren’t usually an inch or two deep into the sediment, but precisely how deep are they?

The depth of fossils varies depending on how deep in a rock formation the fossils are when they’re uncovered. On record, the deepest fossils were found 2,256 meters under the seabed, where the fossil hadn’t been touched in about 200 million years.

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If you want to learn more about where dinosaur fossils are usually found in a rock formation, this article is for you. We’ll talk about rock layers and how paleontologists know whether a rock formation has any potential dinosaurs. We’ll even discuss if you could find dinosaur bones on your property and what to do if it ever happens.

Let’s get started!

A layer of dinosaur bones being excavated in China

What Layer of Rock Are Dinosaur Bones Found In?

Suppose you ever get to visit such esteemed dinosaur fossil locations as the Morrison Formation in Colorado or any place like it. In that case, the layers of rock you’ll witness are multi-layered. That’s how these formations develop in the first place.

What will begin as one layer of rock becomes a second, then a third, and sometimes more.

Not all rock is the same. The three types of rock are metamorphic, sedimentary, and igneous. Let’s examine the three types now.

Metamorphic Rock

The first type of rock is known as metamorphic rock. These rocks undergo metamorphism, which changes the rock’s texture and mineral composition.

The rock that becomes metamorphic rock is originally a protolith, another word for a rock that has yet to undergo metamorphism.

When exposed to temperatures exceeding 300 degrees Fahrenheit and at high pressures, usually over 1,000 bar, the chemical and physical properties of the rock are altered. The rock will stay solid enough, but recrystallization will occur to an extent.

How deep do you need to dig for dinosaur bones

Sedimentary Rock

Next, there’s a sedimentary rock, which forms in a fascinating way.

The earth’s surface (or what at the time was the surface) will have organic particles or minerals deposited on it. Then, ions that travel through groundwater will reach the areas from one sedimentary grain to another and develop a crystalline material in texture.

A process that accomplishes this is called cementation. Through cementation, sediment grains are strengthened and bonded together. Hence, sedimentary rocks are formed.

Not all sedimentary rock is the same. Here is an overview of the various types.

  • Chemical sedimentary rock: If the mineral constituents of sedimentary rock have a high chemical solution concentration, then chemical sedimentary rock can form. Gypsum, baryte, sylvite, and halite are examples of chemical sedimentary rock.
  • Biochemical sedimentary rock: Organisms might grow tissue from materials dissolved in either water or air. For example, diatoms and radiolaria have a silicone skeleton that may leave chert deposits. These deposits are biochemical sedimentary rocks.
  • Mudrocks: When sedimentary rock includes clay and silt particles at a rate of 50 percent or higher and the particles have a fine-quality grain, that’s mudrock. Mudrock occurs when air or water moves quickly, spreading the particles and causing them to move outside of their normal suspension.
  • Classic sedimentary rock: Classic sedimentary rock formations form when clasts or rock fragments undergo cementation, as described above. The clasts may contain mica, clay minerals, feldspar, or quartz grains.

Dinosaur fossils are most likely found in sedimentary rock of the three rock layers.

Digging dinosaur bones out of the ground

Igneous Rock

Finally, there’s an igneous rock, often referred to as magmatic rock. When lava or magma settles on a surface, it doesn’t burn infinitely. Rather, the lava eventually cools and then becomes igneous rock.

Without igneous rock from oceanic crust to the extended crust, igneous provinces, basins, orogens, platforms, and shields, these geographic structures wouldn’t be possible.

How Do You Know If a Rock Has a Fossil In It?

Paleontologists don’t simply dig up every layer of sedimentary rock, hoping to find dinosaur fossils. That could be massively destructive to structures and formations around the world.

Rather, paleontologists will use drones to survey landscapes that might be viable dinosaur fossil locations but are hard to reach. They can also determine if an area may have fossils through ground-penetrating radar.

Upon digging, the paleontologist will closely study the structure of the rock and decide if it’s worth evaluating and chiseling further.

Here are the criteria that’s used.

Test the Weight

Understanding now how sedimentary rock is formed, you can see how the structure of the rock changes over time, so too would the structure of a dinosaur fossil. Indeed, the fossil becomes mineralized.

Thus, a fossilized piece of rock will usually be heavier than a piece of rock of the same size and material that doesn’t contain a fossil.

Morrison formation holds dinosaur bones

Check the Surface

Where did the piece of rock come from that could contain a fossil? What does the rock’s surface look like relative to the nearby rock structure it came from?

If the rock’s surface is textured in any way, then that piece of rock may contain a fossil. Compare that to smoother rock, which is more than likely not a fossil. That’s regardless of the rock’s shape.

Color Inspection

The color of a piece of rock can also indicate whether it’s a fossil. A piece of rock with a lighter color is typically not a fossil, even if that rock feels heavier than other pieces of rock recovered from the same formation.

The only exception is if the rock happens to contain a noticeable fossil imprint, such as a limestone fossil shell.

Instead, darker colors are indicative of fossils, although not exclusively.

Pore Check

Finally, to confirm their suspicions of whether the rock may contain fossils, paleontologists will review the pores of the rock.

Like your skin has pores, rocks do as well. So too do bones have pores, although bone can also be dense depending on the type of bone in question.

A lack of pores could mean a paleontologist has found petrified wood, whereas the presence of pores might be a sign that it’s a porous fossil.

What Happens If You Find Dinosaur Bones on Your Property?

If you read our article on dinosaur fossil finds across the continents, you’ll recall that North America is frequently a popular spot for dinosaur fossils.

That’s not only in rock formations like Dinosaur Ridge, Petrified Forest National Park, or the abovementioned Morrison Formation.

In some instances, dinosaur fossils could be in your yard or elsewhere on your property. It does happen, especially due to soil erosion.

Dinosaur fossils that have been dug out of the ground

What if you find yourself in the unlikely but fortunate predicament of locating a dinosaur bone buried under your property?

Well, first, we would caution you to ascertain whether it’s truly a dinosaur bone. The methods mentioned above are a good place to start.

Once you’re positive you have a dinosaur fossil, what does that mean? Do you have to turn it over to the authorities? Your local museum?

No, you do not. Since your home is private property and the dinosaur fossils were found on that private property, the government cannot get involved. The government only deals in public property.

That means you can do whatever you want with the dinosaur fossils. If you want to keep them and display them around your house, you can. Should you want to sell them for a huge sum, that’s another option.

If you are indeed in possession of bonafide dinosaur bones, then you can expect quite a bidding frenzy. Dinosaur fossil collectors and professionals alike will be eager to see the bones. You could earn enough money to pay off your mortgage or put your child through college, maybe even both.

Our recommendation, should this predicament ever befall you? Keep the fossils if you must, but lend them to paleontologists or dinosaur experts for further study.

The fossil you found could be the only one of its kind. It could complete a skeleton for a dinosaur that still has a few missing parts, or perhaps the fossil is a discovery of a new species.

It’s nearly impossible to say for sure without experts studying the fossil. For the good of dinosaur fans everywhere, allowing professionals to assess the fossil can further the world’s knowledge of dinosaur species. That’s always worthwhile, we think.


Many dinosaur fossils that are unearthed come from sedimentary rock, one of three major rock types. In some rare instances, fossils have been buried deep under the seabed, where they may remain undisturbed over millions of years.

Sometimes finding fossils is far less complicated than that, as they could be in your backyard, especially if you live near a well-known rock formation!