The first fossilized dinosaur eggs found (and the biggest yet to be found) were football-shaped Hypselosaurus eggs found in France in 1869. These eggs were 1 foot (30 cm) long, 10 inches (25 cm) wide, had a volume of about half a gallon (2 liters), and may have weighed up to 15.5 pounds (7 kg). The smallest dinosaur eggs are about 1 inch across; they are from Mussaurus.

Many fossilized dinosaur eggs have been found, at over 200 sites in the USA, France, Spain, Mongolia, China, Argentina, and India. Very rarely, the eggs have preserved parts of embryos in them, which can help to match an egg with a species of dinosaur. Without an embryo, it it difficult to match an egg to a dinosaur species. The embryo in an egg sheds light on dinosaur development.

FOSSIL OR ORIGINAL SHELL?
According to Dr. Kenneth Carpenter, most dinosaur eggshells still have the original shell, not a fossilized replica, "The slightest change in the calcite making up the shell destroys the very fine detail that can be seen with the scanning electron microscope. Amino acids have also been recovered that are very similar to those found in modern bird eggshell."

RECENT FINDS
About 10 large dinosaur eggs (plus 3 egg impressions) were found 1999 in southwestern France (near Albas, in the foothills of the Pyrenee Mountains). No bone fossils were found. The eggs had been buried in two layers in the sand. No one knows what type of dinosaur the eggs were.

Much larger egg sites have been found nearby, in northeastern Spain near Tremp, where hundreds of thousands of eggs (of both sauropods and theropods) have been found. Other huge dinosaur eggs sites have been found in Argentina and China.

NESTS

Many Maiasaura nests have been found in Montana, USA; nests, eggs, hatchinglings, juveniles, and adults were found in one area. This fossil evidence indicates a high level of parental care and a very social dinosaur.

Fossils of dinosaurs' burrows and nests can reveal a lot about their behavior. Nests vary from simple pits dug into the earth or sand to more complicated nests constructed with mud rims. They may appear in large groups or all alone. The nests and the clutches of eggs reveal information about the dinosaur's nurturing behavior.

HOW DID THE GIANT SAUROPOD LAY THEIR EGGS
One of the many unanswered questions about dinosaur reproduction is how the giant sauropods (like Apatosaurus, Diplodocus, and Brachiosaurus) laid their eggs without breaking them. Even if the sauropod squatted while laying eggs, the eggs would be dropped from a height of roughly 8 feet (2.5 m). Some scientists have theorized that females may have had tube that extended from the body for laying eggs (some modern-day turtles have a tube like this).

Dinosaur Length of Adult	Where Fossils Were Found	Egg Shape, Size	Egg Placement	Were the Eggs in a Nest?	More Information
Hypselosaurus 27 feet (8 m)	France	Football-shaped, 1 foot (30 cm) long, 10 inches (25 cm) wide, had a volume of 5.8 pints (3.3 liters), and may have weighed up to 15.5 pounds (7 kg)	Group of 5	No	This was the first dinosaur egg discovered and the largest.
Hypsilophodontids 7 feet (2.1 m)	Montana	Potato-shaped, 6 inches (15 cm) long	.	Yes	.
Maiasaura 25-30 feet (7.8-9 m)	Montana	Oval, Grapefruit sized, 8 inches (20 cm) long	15 to 25, arranged in a circle	Yes	The nests were holes scooped out of the ground, about 6-7 feet (1.8-2 m) in diameter, and about 3.5 feet tall. Newborns were about a foot (0.3 m) long. Nests were placed about 25-30 feet (7.6-9 m) apart, just about the size of an adult Maiasaura. In Montana, one group of over 40 nests covers 2.5 acres (1 hectare) of land that was an island during the late Cretaceous period.
Mussaurus 10 feet (3 m)	Argentina	1 inch (2.5 cm) long	5 in a group	Yes
Protoceratops 6 feet (1.8 m)	Mongolia	Potato-shaped, 6-8 inches (15-21 cm) long	12-30 eggs in a spiral	Yes	The nest was a shallow pit dug in the sand.
Sauropods over 100 feet (30 m)	Many locations	Football-shaped, up to 1 foot (30 cm) long and 10 inches (25 cm) wide	Usually laid in a row (as though the dinosaur laid them while walking.	Rarely	.

ZoomDinosaurs.com DINOSAUR ANATOMY AND BEHAVIOR

General Anatomy

Size

Teeth

Herds, Packs

Offense

Defense

Reproduction, Nests & Eggs

Blood Pressure

Skeleton

Tails

Brains

Male or Female?

Skin

Diet

Locomotion

Life Span

Hot or Cold Blooded?

• Eggs with embryonic Therizinosaurs (bipedal meat-eaters, a theropod from the late Cretaceous) were found in 1991 in central China.