First evidence that dinosaurs laid colourful blue-green eggs

May 28, 2015

Image: Tzu-Ruei Yang, University Bonn

By Jeff Hecht

The American robin lent its name to a striking shade of blue, but the vivid hue may have been colouring eggs long before the bird evolved – perhaps long before any birds evolved. It may have appeared in the dinosaur ancestors of birds that lived 150 million years ago.

Although recent studies have revealed the colours of dinosaur feathers, skin and scales, we had known nothing about the original colour of their eggs.

Ornithologists once assumed early birds, and the dinosaurs they evolved from, laid white eggs. But we know that some of the most ancient groups of birds still around – including the tinamou and emu – actually lay coloured eggs, points out Mark Hauber, an animal behaviourist at Hunter College in New York.

His group has discovered the chemical origin of the avocado-green from emu’s eggs, as well as the blue of robin’s eggs, the brown of chicken’s eggs and the pinks and purples from the eggs of other birds belonging to ancient living groups. The colours come from the way that two pigments in the shell – biliverdin and protoporphyrin – blend with each other and with the calcium carbonate that makes most of the shell.


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9 comments on “First evidence that dinosaurs laid colourful blue-green eggs

  • From the OP

    Egg colour has other benefits: it can help the parent recognise and eject eggs that another species might add to the nest surreptitiously – like cuckoos and cowbirds do today. The protoporphyrin also helps strengthen the shells.



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  • I am gratified that science is now beginning to provide support for my hypothesis that Barney was a real historical character. It might also shed some light on that difficult conversation I had with my mum in my mid teens, and that those stains on the sheet really were the missing parts of the Barney shroud, etched into its fabric on his death.
    I may be owed an apology, or some therapy.



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  • Also have to consider that the part of the spectrum they, or those animals likely to eat them may not be exactly the same as ours (although the comment about being able to reject them speaks against this). The same must be true of emu who also don’t have nests and who also have distinctly coloured eggs. But if we consider that some animals that preyed upon the eggs may not have had the full range of colours visible to them as us then the bright blue or green may just be another shade as hard to distinguish as a chart for a colour blind person.



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  • Very Good headswapboy;)

    I wish I’d thought of that but we didn’t get Barney here Down under.

    Many a boy I suspect has taken an interest in washing their own bedding in their teens, My mum thought I was turning over a new leaf and taking some responsibility for housework at last.



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  • That would make sense; the eggs that stood out to predators would have been eaten. We already know that many birds lay eggs that blend in with the background, such as the grey speckled eggs laid on a cliff by seabirds. Laying eggs keyed to the colors that predators couldn’t see is an interesting twist.



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