Learn How Dinosaur Eggs Are Fossilized And Identified


There are a lot of fascinating things to learn about Dinosaurs ranging from how they dinosaurs came to be, what happened to them, what they looked like and a lot of other interesting facts. In this article, you will be learning how dinosaurs Eggs are fossilized and also how to identify dinosaur’s fossilized eggs.

So, How are Dinosaurs Eggs Fossilized and How Do You Identify Fossilized Eggs? Fossilization occurs when a dinosaur laid eggs in an environment that had lots of moving sediments. This sediment quickly buried the eggs, offering its body some protection from decomposition. After the organic materials have disappeared, a fragile, porous mineral will form in the shape of the original egg.

However, the best way to identify fossilized dinosaur eggs is to involve a professional as they are in the best position to determine whether what you found is a real fossilized egg or just a rock.

Read on for more information on how dinosaur eggs are fossilized and how to identify facsimiled dinosaur eggs.

How Dinosaurs Eggs Get Fossilized

Before we go into the process through which dinosaur eggs become fossilized, first we need to examine the conditions for fossilization. There are several specific conditions that have to be in place for an embryo to fossilize. These are:

  • First, an egg containing a healthy embryo has to be buried in sediment. A freshly laid egg, which has no visible embryo, or one that has started to rot will not do.
  • The egg also has to be intact — if there’s a crack in the shell big enough for anything to escape, the material inside will leak out before fossilization can occur.
  • Finally, the buried egg has to survive the slow process of fossilization. Groundwater containing minerals seeps through the shell, replacing the nonmineral components of the bones inside.

Most of the time, soft tissues and fluids inside the egg break down or dissipate instead of becoming fossils. The shell itself is already made of calcium, so it doesn’t physically change much during the fossilization process. But, if all goes well, the embryonic skeleton inside turns into rock.

Process of Fossilization

Fossils are formed and found in the crust, which is the thinnest layer, that forms the Earth’s surface. The majority of the rocks found in and on the Earth’s crust are sedimentary rocks. They form when sediments, like silt and sand, collect and harden, which over the course of millions of years, results in thick layers of sedimentary rock.

Dinosaur fossilized eggs are formed when a dinosaur laid eggs in an environment that had lots of moving sediment, like an ocean, riverbed or lake. One such place is the benthic zone — the deepest part of a body of water. This sediment buries the eggs, offering its body some protection it from decomposition.

However, a buried egg isn’t the same thing as a fossil — to become a fossil, the egg has to become rock. The organic parts of the egg eventually break down. But the inorganic parts remain after the organic materials have disappeared, creating a fragile, porous mineral in the shape of the original egg.

During decomposition, Other minerals reinforce the egg, burning into a fossil. Water gradually makes its way to the egg, carrying minerals like iron and calcium carbonate picked up from the surrounding sediment. As this process continues, the bone becomes more and more rocklike.

The whole process is like filling a sponge with glue – the sponge’s physical structure stays the same, and the pores and pockets within it fill up. The glue makes the sponge sturdier and more resistant to damage.

Over the course of millions of years, the sediment around these reinforced eggs becomes sedimentary rock. Erosion, tides and other natural processes continue to deposit more sediment, and this sediment becomes rock, too.

As long as they can withstand the pressure from the surrounding rock, the eggs remain safely hidden and preserved. After millions of years, some natural process, like the gradual shifting of the planet’s surface, can reveal these layers of rock and the fossils they contain.

How to Find Fossilized Dinosaur Eggs

To find fossils in sedimentary rock, you will have to hunt for layers of rock that are the same age as the fossils you want to study. To do this, you’d consult a geologic map that displays the locations, features and ages of rock formations.

Once you find the right rock, finding a fossil requires luck and a good eye. Fossilization is a relatively rare occurrence, so if you don’t find anything at the end of the day, don’t be too discouraged. However, if you really do find a fossil, the next step will be excavation and preparation.

How to Identify Fossilized Dinosaur Eggs

To the untrained eye, a collection of fossilized eggs might as well be a pile of pebbles. Even for the professionals, identifying fossilized eggs might get pretty confusing. So, how do you make sure that what you have is actually the real deal?

  • The first thing to ask when determining if you have found fossilized eggs is the location. Dinosaurs fossils can only turn up in particular rock formations in certain areas around the world.

Using data from the Paleontology Database, Interactive map can show you everywhere on Earth where dinosaur fossils have been found.

  • Genuine fossil eggs usually have an easily identifiable shell which differs significantly from the enclosed sediments either by having a fine surface ornamentation or a specific type of crystalline structure in cross-section.
  • The thickness of the fossilized eggs should be roughly uniform, they are usually slightly curved, and their surface is covered in tiny pores to facilitate gas exchange. To confirm the pores, take a magnifying glass over the “shell” and see if you can see the pores. If the shell is too thick and you can’t find any pores, then you are most likely looking at a rock.
  • Also, because eggshell tends to be brittle, the shell is almost always heavily cracked with clear shifting of the eggshell bits. Ironically, if the fossilized eggs are very egg-shaped, then it most likely won’t be the real thing.
  • As a last resort you can confirm your fossilized egg by licking it. By just taking a quick tip of your tongue on the egg, you can possibly identify whether what you have is real or not. Fossilized Dinosaurs eggs are expected slightly stick to the tongue. A fossil will be stickier than an ordinary rock because of its porous nature.

False Eggs that can be easily be mistaken as fossillized dinosoaur Eggs

  1. Calculus: Calculi are egg-like objects formed in the stomachs of ruminants such as cattle, deer and goats. Calculus formation is a defense mechanism protecting the ruminant’s stomach from damage if it swallows a foreign object while grazing.

After ingestion, the object is covered by the same material composing bone, calcium phosphate and eventually vomited out of the animal’s system. These “stomach stones” tend to range in size from 1 to 6 centimeters. Larger sizes are known but very rare.

In some cases, it has tiny dimples cover the surface of a stomach stone, which can fool observers into thinking they are the pores of a fossilized egg.

Calculi can be distinguished from real egg fossils because when they are broken open, they show the layers of calcium phosphate and the foreign object at the core. Calculi are also often suspiciously intact, unlike fossil eggs, which are usually damaged.

Furthermore, they also lack distinct shells and structural components such as continuous layers, mammillae, and pores associated with fossilized dinosaur eggs.

  • Concretions: these are formed when decaying organisms change the chemistry of their immediate surroundings in a manner that is conducive to minerals precipitating out of solution. These minerals accumulate in a mass roughly egg-shaped.

Concretions also generally lack distinct shells and eggshell structures like pores, mammillae, and layers. Also, concretions are mostly larger than any real fossilized dinosaur egg.

  • Insect trace fossils: Sometimes the living or breeding chambers of an insect burrow are so perfectly egg-shaped that even a paleontologist can mistake a natural cast of these chambers for a fossil egg.

Insect burrow fossils can sometimes be distinguished from real egg fossils by the presence of “scratch marks” on their surface left by the insect during the burrow’s original excavation. Fossil insect pupae can also resemble eggs.

After death and burial, the decomposition of a deceased pupa would leave a gap in the sediment that could be filled with minerals carried by groundwater, forming an egg-like cast. These pseudo-eggs can be recognized by their small size (usually not much longer than a centimetre or two) and lack of an eggshell with its typical anatomy.

  • Stones: The erosive effects of water can sometimes round rocks into egg-like shapes.

How To Spot Fake Dinosaur Eggs 

First, the best way to avoid fake eggs is to go and collect them yourself. However, always make sure to follow the laws and have permission to collect before proceeding. In the United States, typically a good way to follow the law is through collection on private land with expressed permission from the landowner.

Views of palaeontologists do range on private ownership of fossils with many not condoning or endorsing. However, if you are going to buy, do everything possible to ensure the egg or any fossil was legally collected.

Often with fake eggs everything seems too perfect. Eggs are delicate and easily crushed or damaged so if there are no signs of any damage or natural alterations be very wary. If the surface has ridges, check to see those ridges continue across a crack or break of the shell.

Many fake eggs are mosaics made up of real eggshell fragments assembled together in an egg shape. These mosaics tend to not have the eggshell match on opposite sides of a crack. If you would like more information beyond what is provided or have an unanswered question, feel free to start a thread.

If after reading, you want to purchase an egg then please ask the seller for the best pictures they can provide of that egg with something to show scale such as a ruler and start a thread.

Finally, if you are still not sure after all of this, then it will be best to involve a professional. That way you are better assured of getting the real thing at the end of the day.

Michael Haralson

I'm the owner of Adventure Dinosaurs website. Although I have an extensive business background, I am fascinated with dinosaurs and have been since childhood. I'm fortunate enough to have visited fossil museums in Europe (UK, Germany, and Spain), the US (California, Texas) and in Asia (China). Currently, I'm location independent with a home base in Kirkkonummi, Finland.

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