Dinosaurs are an ongoing source of fascination for all ages and their eggs give some tantalising clues about them. Discoveries of fossilised dinosaur eggs have given scientists great insights into how dinosaurs reproduced and hints as to their social behaviour.
Model of Maiasaura nest in Natural History Museum, London (Wikipedia Creative Commons)
The first fossilised dinosaur eggs were found in 1923, but discoveries were quite rare until the 1980’s and now eggs have been found on most continents and for many different species. The difficulty may have been that there would only be broken remnants fossilised to find after dinosaurs hatched and whole fossilised eggs may be overlooked as they often resemble other geological formations, such as sedimentary concretions or smoothed river rocks.
It is rare to find fossilised embryos inside eggs which would help to identify the species. This first video below shows David Attenborough explaining how the discovery of one fossilised embryo gave clues on how baby dinosaurs broke out of their eggs. The second video is an excerpt from the excellent BBC Earth series ‘Walking with Dinosaurs’, showing how the discovery of some pieces of eggshell led to finding a rare embryo of a large carnivore.
This article from the Washington Post explains that sometimes it can take many years after a fossilised embryo has been discovered to identify the species of dinosaur, especially if they are not found with adult examples of their species. This was the case for the fossilised embryo mentioned in the article and pictured below, which was nicknamed ‘Baby Louie’.
Baby Louie - a Beibeilong fetus in the Children's Museum of Indianapolis (Wikipedia Creative Commons)
Nests and parenting behaviour
There have been many fossil discoveries of carefully arranged nests of eggs showing that some dinosaur species were attentive parents. Some sauropod nests have been found with up to 28 eggs in them of the same size, indicating they were most likely laid in one sitting.
There have also been places where many nests have been found together, indicating some species nested in colonies. Although it is not possible to tell from the fossil evidence, perhaps parental care of hatchlings may have been shared in these colonies.
As with modern bird species, there is a great variety in the shape and size of fossilised dinosaur eggs found. There is some evidence that dinosaur eggs may have been coloured also. Chemical analysis and a non-destructive technique called Raman microspectroscopy has found traces of pigments in fossilised eggs from some dinosaur species, whilst others showed no pigment traces. This has led to the assumption their eggs were white. More information can be found in this article.
Some dinosaur eggs are textured and many have been found to have porous shells to allow moisture and gases to travel through the shell. It is thought that many species buried their clutches of eggs in a similar fashion to modern crocodiles to help with incubating the eggs.
Spherical dinosaur eggs in Senckenberg-Museum, Frankfurt (Wikipedia Creative Commons)
Oblong dinosaur eggs in Kunming Natural History Museum of Zoology (Wikipedia Creative Commons)
Make your own dinosaur eggs
Would you like to make and hatch your own dinosaur eggs? Watch this PALMS video Dinosaur Eggs – Two Ways to find out how. The supporting PALMS teacher notes can be found here.
Dinosaur eggs – two ways
Learn more about dinosaurs and their eggs:
- Research on fossil eggshells by scientists from the Royal Tyrrell Museum, Canada and others provides evidence of warm body temperature in dinosaurs
- Dinosaur Discovery – Lost Creatures of the Cretaceous – Easy to read information from the 2014 exhibition at the Western Australian Museum
- Virtual tour of the American Museum of Natural History (including lots of dinosaur skeletons!)
- Facebook live video from American Museum of Natural History of paleontologist Danny Barta talking about dinosaur growth and showing some of their exhibits