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Dinosaur Eggs with Embryos Still Inside – The Surprising Discoveries

Dinosaur eggs can give us a fascinating glimpse into what certain species were like in juvenile stages. Sometimes, paleontologists will get lucky and find a dinosaur egg with an embryo still inside. What can we learn from these discoveries?

The existence of dinosaur eggs with embryos still inside indicates that perhaps not all dinosaurs hatched from eggs. At present, dinosaur experts believe that most dinosaurs laid eggs, especially theropods. Some live births could have occurred, though. 

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If you’re interested in learning about dinosaur eggs with embryos intact, this article is for you. We’ll discuss Baby Louie, the most famous of such fossil eggs, and other dinosaur egg embryos that contained an embryonic skeleton. Make sure you keep reading! 

Dinosaur Eggs with Embryos Still Inside_AdventureDinosaurs

Has a Dinosaur Embryo Been Found? The Fascinating Story of Baby Louie

Of course, we can’t talk about dinosaur embryos without mentioning Baby Louie, which is perhaps the most famous embryo of its kind.

Baby Louie was recovered in the early 1990s in China’s Henan Province. When the embryo was found, it was encircled by other eggs.

Unlike those eggs, though, Baby Louie had a petrified embryo intact.

The eggs were fascinating, too, as they had an average width of six inches and 18 inches. If that sounds especially big, even for a dinosaur egg, that’s because these extraordinary eggs were indeed big.

In fact, as of this writing, no larger dinosaur eggs have been found. Baby Louie was in good company.

Where were the remains of any parents, you might wonder? Well, paleontologists couldn’t find the parents. Thus, we’ve had to wait decades and decades for any further information on Baby Louie.

Today, we finally know more about Baby Louie’s lineage. 

Baby Louie is a giant oviraptorid dinosaur, which looked like an ostrich or cassowary but was about the size of an elephant. 

Oviraptor dinosaur eggs have been found in the Gobi desert

Paleontologists classified Baby Louie as his species known as the Beibeilong sinensis, aka the Chinese baby dragon.

What about the eggs that surrounded the embryo? Those eggs, the paleontologists said, were Macrolongatoolithus eggs.

Macrolongatoolithus is a theropod egg oogenus mostly hailed from Asia but found in North America. 

Some of the locations the eggs have been uncovered include the Goseong Formation in South Korea, the Zoumagang Formation in China, the Willow Tank Formation in Nevada, the Thomas Fork Formation in Wyoming, the Blackleaf Formation in Montana, the Wayan Formation in Idaho, and the Kelvin Formations in Utah. 

The eggs are laid in a nest of up to 30 at once, and Baby Louie was the critical piece of the puzzle that unlocked more information about Chinese baby dragons. 

This excited paleontologists. After all, if Baby Louie could have survived in a skeletal condition for millions of years, then perhaps more fossilized dinosaur eggs with embryos still inside could be out there. 

Sauropod Dinosaur Eggs with Embryos

Baby Louie may be the most noteworthy dinosaur with an embryo still inside, but the good news is that he’s not the only one.

In parts of the world, such as Argentina and Spain, hard-working paleontologists have further fueled our knowledge of dino embryos, especially sauropod embryos.

Sauropod eggs vary from tyrannosaurid eggs in that several nests of eggs of the former have been found, while no nests for the latter have ever been located. As a species, sauropods were long – from the head to tail, an adult could reach lengths up to 130 feet.

Tyrannosaurids are believed to have laid eggs, but more evidence is needed.

In the meantime, we have gained plenty of evidence of sauropod egg embryos, and all quite recently too! Let’s take a closer look.

In Argentina

The Argentinian discovery of long-necked sauropod dinosaur eggs with embryos was recent, having only happened in 2020.

Paleontologists came across a nesting ground full of titanosaurian sauropod dinosaurs presumed to have lived during the Cretaceous Period about 80 million years ago.

The location of the found embryos means that the dinosaurs of the age would have lived in what is modern-day Patagonia.

A report from late 2020 in the journal Current Biology goes into more detail on one of the skulls, as it’s truly a marvelous specimen.

The skull, which was still in its embryonic stages, was almost entirely intact. As we’re sure you can imagine, the amount of information contained in this skull is enormous.

Paleontologists can now confirm that the titanosaurian sauropod embryos had a long front facial horn that disappeared as the dinosaur age.

By the time these dinosaurs reached adulthood, any horn traces were gone.

Further, from the embryo, paleontologists could deduce that titanosaurian sauropod babies boasted stereoscopic vision.

Known as stereopsis, stereoscopic vision would have allowed a dinosaur to use its eyes to determine structure depth, including how 3D a structure was.

Paleontologists couldn’t confirm whether the intact embryo skull they found could be a different species. It doesn’t look like the paleontologists’ sauropod embryos uncovered in Patagonia, but that has yet to be confirmed.

Due to the extreme rarity of intact embryo skulls, this was a very, very lucky find.

In Spain

Around the time of finding Argentinian sauropod dinosaur eggs with embryos, a similar thing happened in Spain, particularly in the Aragon area.

In 2020, a dinosaur nest was uncovered in the northern part of Aragon. The paleontologists who found the eggs believe that they were about 68 million years ago. They did not find a complete skeleton but found many fossilized eggs.

What’s unique about this finding is that all the eggs were unhatched. There were about 20 eggs in all.

The average size of the eggs found in the nest was eight inches in diameter. Paleontologists think that, due to the size of the eggs, titanosaur sauropods would have laid the eggs.

So why didn’t the eggs ever hatch? That’s hard to say. Perhaps the conditions weren’t amenable enough, but we’re only hypothesizing.

According to a 2017 article from, a dinosaur would take roughly three to six months to hatch from an egg.

Thus, if more than 65 million years have gone by from the time the eggs were deposited to now and the eggs still haven’t hatched, the Spanish paleontologists in Aragon are fairly confident it will never happen.

This finding is noteworthy due to the amount of time the paleontological team dedicated to the search. For more than 15 years, they looked for dinosaur eggs across Aragon. They only found the nest of eggs by stumbling upon it.

The number of recovered eggs surpasses the paleontological team’s highest expectations.

Since the eggs were recovered, we haven’t had any further information on what kind of dinosaurs may be inside. Thus, we won’t even venture a guess, as it would be pure conjecture at this stage.

What we can say for sure is this. We still know precious little about dinosaur embryos. Any findings of embryos could someday help us paint a broader picture about why some dinosaur eggs hatched, why some didn’t, and why some embryos were preserved. 

What Dinosaur Embryos Can Tell Us About Dinosaurs

So why have more dinosaur embryo findings occurred in the 2020s than in previous years? Technology has advanced and allowed us to find embryos that would have otherwise been missed.

Thanks to current technology, paleontologists and other experts can also deeply study the embryos and get to know entirely what they’re looking at.

For example, going back to the Argentinian titanosaurian sauropod embryo, paleontologists studied the skull to deduce that these dinosaurs had confluent nasal openings, stereoscopic vision, a premaxillary horn, and a monocerotic face.

Sinus confluence refers to the connection of the occipital sinus, straight sinus, and superior sagittal sinus.

Monocerotic is a term that describes an animal or creature with a single horn. For instance, a rhinoceros is monocerotic.

Of course, rhinos are not related to dinosaurs’ shape or form. As for birds? Now that’s a different story.

Baby Yingliang is another fossilized dinosaur embryo found in Jianxi Province in China. The fossil dates back to the Cretaceous Period, between 66 and 72 million years ago. The embryo is likely an oviraptor. It has one of the best-preserved dinosaur embryos, complete with baby dinosaur bones encased within the egg.

The oviraptorosaur was a feathered theropod and is a link between dinosaurs and today’s birds.

Modern birds are known as egg-layers, and they create nests as well, just as some dinosaurs did.

Further, the positioning of the dinosaur within the embryo is very bird-like.

A dinosaur still in its egg would tuck itself in nice and cozy. It is what bird embryos do as well.


Dinosaur eggs with embryos still inside are undeniably rare, but in the 2020s, we have two such discoveries to report. Perhaps more will follow, which would be incredibly exciting.

The information available based on dinosaur embryo discoveries is truly interesting stuff, but we’re just scratching the surface. Hopefully, more embryos will be found sooner than later, so we can learn even more about these dinosaur species!