Some dinosaurs are positively massive. But like most reptiles, these giants don’t start their lives at those titanic sizes — even relatively speaking.
Many species, though perhaps not all, likely came from eggs laid outside their mothers' bodies. But paleontologists have yet to discover the eggs of many dinosaurs. Perhaps unsurprisingly, these highly delicate embryo cradles probably didn’t last more than a few months, let alone the huge epochs of geological time scales.
But regardless, some nests have survived in fossilized form, and in great numbers. Here are some of the largest nests ever discovered.
1. Hundreds of Titanosaur Eggs in India
In January 2023, paleontologists published a study documenting the discovery of 256 eggs from 92 different clutches, or nests. These eggs were found in the Narmada Valley of central India, and date back to the Upper Cretaceous more than 66 million years ago in what may have been a floodplain, the authors of the study published in PLOS ONE write.
The eggs likely belonged to titanosaurs, a diverse group of long-necked sauropods and some of the largest dinosaurs that walked the Earth — perhaps from several species that laid their eggs together in a nesting colony.
Read More: A Stash of Leathery Dinosaur Eggs Tells Us About the Origins of the Giant Reptiles
2. Mystery Eggs in the Southern Pyrenees
In the late 20th century, Spanish paleontologists found the remains of a huge nesting site in the southern Pyrenees in Spain. Jose Luis Sanz, a paleontologist at the Autonomous University of Madrid, and his colleagues found about 300,000 eggs in one large piece of sandstone, in an area that would have been a beach about 65 million to 70 million years ago.
This wasn’t just one nest, either, but at least 24, with randomly dropped eggs. Each nest contained anywhere from one to seven eggs, which were about 8 inches wide on average. The scientists also found small bones that may have been young dinosaurs, but the researchers couldn’t determine the species of the eggs based on the fragmentary nature of the fossils.
Read More: How Did Dinos Lay Eggs and What Were Dinosaur Eggs Like?
3. Mussaurus Eggs in Patagonia
When researchers first found fossils of the Mussaurus, they thought the pigeon-sized creatures were adults. But a discovery of more than 100 Mussaurus eggs, as well as adults, revealed that the initial finds were just babies compared to the SUV-sized adults.
These sauropods lived about 193 million years ago, and according to the discovery in Patagonia, they likely lived in herds, making it among the earliest evidence known for dinosaurs living in herds, the authors of the study said in 2021. The various nests had clutches of eight to 30 eggs each.
Read More: How Sauropods Evolved to Their Enormous Size
4. A Pterosaur Hatchery in China
In 2017, researchers announced the discovery of several hundred ancient eggs in China dating back to more than 100 million years ago. But these eggs, which numbered as many as 300, weren’t dinosaurs but pterosaurs — flying reptiles from from the species Hamipterus tianshanensis.
The high number of eggs was a major discovery especially since paleontologists hadn’t found such high numbers of pterosaur nests in the past. Aside from this milestone, the fossils contained some embryonic remains, giving researchers an idea of what this species looked at various stages in their development.
Read More: How Big Was Quetzalcoatlus and Other Giant Pterosaurs?
5. Egg-Nesting Oviraptorosaurs
One large consortium of nests doesn’t belong to a single site, but they are all from oviraptorosaurs, a group of theropods were closely related to birds. The group first took its name as “egg-eating” since researchers thought a fossil discovered on top of fossilized eggs was there for a snack rather than to nurture in the next generation.
Many of these dozens of nests were discovered in China, coming from the Late Cretaceous between 67 million and 104 million years ago. Most of these nests had up to 30 eggs, but what makes them particularly interesting is the concentric ring pattern they sit in on the nest, presumably allowing the adult to sit on them to incubate without breaking them.
Read More: Why One Extraordinary Collection of Dinosaur Embryos Remains Locked Away From Science
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Sedimentary Geology. Depositional setting and early diagenesis of the dinosaur eggshell-bearing Aren Fm at Bastus, Late Campanian, south-central Pyrenees
Scientific Reports. Earliest evidence of herd-living and age segregation amongst dinosaurs
Science. Egg accumulation with 3D embryos provides insight into the life history of a pterosaur
Biology Letters. Incubation behaviours of oviraptorosaur dinosaurs in relation to body size
Joshua Rapp Learn is an award-winning D.C.-based science writer. An expat Albertan, he contributes to a number of science publications like National Geographic, The New York Times, The Guardian, New Scientist, Hakai, and others. Find him on Instagram.
