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Fossil hunter Raimund Albersdörfer in an interview

At Easter, egg hunts are part of the tradition. How likely is it to come across a dinosaur egg?

I have to discourage you. That is highly unlikely. Dino eggs are extremely rare, you’re more likely to find bones, teeth, or a complete dino skeleton. There are only a few sites worldwide, for example in China, Argentina or France. Not a single egg has yet been discovered in Germany, not even a fragment of the shell. Finding an egg here would be a sensation, the jackpot for fossil hunters.

Why are dino eggs so rare?

Most of the eggs have either been destroyed when the animals hatched or by predators. What you can still find today are eggs spilled by shifting sands or landslides, which fortunately were not completely crushed. One should also consider that they happen to be more than 60 million years old.

In Hollywood movies, the heroes often discover dinosaur eggs, which they hatch and hatch into baby dinosaurs.

This is of course complete nonsense. Everything discovered today has been fossilized for millions of years. DNA, i.e. the substance that contains the genetic material, is an organic compound that irrevocably decomposes after a relatively short period of time.

Dinosaur eggs are not very big, many are about the size of soccer balls.

That’s right, compared to the size of adults, dinosaurs tended to lay small eggs. For comparison, mammals weigh a few percent of their mother’s weight at birth. If a giant, long-necked dinosaur weighing 50 tons had been able to give birth to babies as large as a mammal – say a human – the baby would have weighed about 2.5 tons. The egg would have to measure more than 1.5 meters in diameter.

Why aren’t the eggs bigger?

The birth canals of the female dinosaurs were relatively narrow, they had very specially designed pelvises. There wasn’t much room for giant eggs. It was also important that the eggshells were neither too thick nor too thin. After all, they were often thrown onto the ground from a great height and were not allowed to break in the process. The thickest shells ever found are about 0.6 centimeters thick. Thicker eggs would not have been air permeable enough, the embryos would have suffocated. There are so-called “dragon eggs” that look a bit like American football balls. They are oblong and up to 40 centimeters long. This shape made it possible for the eggs to contain as much yolk as possible to nourish the embryos. Those were real yolk bombs. It is believed that T-Rex laid eggs in this shape.

How can one imagine the incubation of the eggs?

Of course, no Diplodocus weighing forty or fifty tons sat on an egg to hatch. The shells would have to be dozens of centimeters thick to withstand the pressure. The large dinosaurs probably laid their eggs in warm, sheltered places in sand hollows and let them hatch in the sun. Only particularly birdlike dinosaurs hatched their eggs.

Since they were easily eaten by other dinosaurs?

We believe that herds of herbivorous dinosaurs protected and probably defended their nest sites against monitor lizards or smaller dinosaurs. The eggs of large long-necked dinosaurs are often found in loose clusters, but sometimes strung like a string of pearls. They probably laid their eggs while walking and did little brood care. More bird-like dinos like Oviraptor and maybe even T-Rex – or at least many of its relatives – probably engaged in active brood care. Their nests sometimes contained 30 or 40 eggs, often in several layers on top of each other in a closed circle. It is not unlikely that female tyrannosaurs cared for their offspring with dedication and love.

They often use words like “suspect” or “probably”. It seems like the dino egg research is not very far.

There are still many mysteries in the scientific processing of the eggs of these giant lizards. Much is unclear. Were the eggshells soft and leathery, or hard? Why is there no trace of eggs for whole subgroups of dinosaurs like Stegosaurus or Triceratops? In general, it is not easy to determine which dinosaur genus an egg came from. Only very rarely are the bones of the adult animals in the immediate vicinity. Even when the skeletons of unhatched embryos are preserved in the eggs, they bear little of the characteristics of adult animals. Science is therefore reluctant to name it. It is these puzzles that create the fascination.