The Discovery of Blue Dinosaur Eggs Puts Bird Evolution in a New Light

Fagjun | Published 2017-09-30 01:57

These blue dinosaur eggs indicate that the large prehistoric animals were closer to birds than originally thought.


A bird-like dinosaur may have laid blue eggs. [Photo by Tzu-Ruei Yang, The Paleowonders Museum of Fossils and Minerals, Taiwan]



What's so special about dinosaur eggs that happen to be blue, you ask? There have been long-standing assumptions that dinosaurs laid white eggs. Most birds and all reptiles do. Even the platypus and echidna, the only egg-laying mammals, lay white eggs. Robins are famous for their blue eggs, but this egg color may not make them all that special. After all, a dinosaur species did it first.


But, again, what's the big deal about egg color? Because most bird and reptile eggs were white, scientists assumed that colored eggs evolved in modern birds after non-avian dinosaurs went extinct. Also, the color of the eggs may indicate that fathers watched over the eggs instead of the mothers.


Fossilized eggshells from China indicate that an ostrich-like feathered dinosaur likely laid clutches of blue-green eggs.



Heyuannia huangi


A close-up of the eggs [Photo by Tzu-Ruei Yang, The Paleowonders Museum of Fossils and Minerals, Taiwan]

According to a new study, an oviraptor species named Heyuannia huangi laid these blue eggs, the color likely functioning as a camouflage. Heyuannia nests, after all, were open holes dug into the ground. Heyuannia had a beak like a parrot, walked on its hind legs, and had been about five feet long.


Fossilization, unsurprisingly, doesn't let dinosaur eggs keep their original color. Dinosaur egg fossils are either black or brown. However, the Heyuannia egg fossils had a blue tint to them. Scientists thus wanted to know if the egg shells retained at least some of their original color.


It was mass spectrometry that allowed the researchers to confirm that the eggs had indeed been blue. The researchers were able to find two pigments—biliverdin and protoporphyrin. These two pigments are present in modern bird eggs. Biliverdin, which comes from a bird's bile, causes a blue or green color. Protoporphyrin, meanwhile, gives egg shells a red or brown color, as well as speckles.


"We screened through lots of eggshells, and one day had a positive result for these oviraptor eggs,” says lead researcher Jasmina Wiemann. “It was a huge surprise. I couldn't believe it."


Confirming the color of the eggs also gave scientists an idea of what the behavior of Heyuannia could have been.



What Dinosaur Eggs Can Tell Us


An emu father tends to his blue-green eggs. [Photo via Websters Wildshots]



Ostriches, cassowaries, and emus lay eggs whose color facilitate camouflage. These birds lay their eggs in large, open nests in the ground, much like the Heyuannia. Among ostriches, cassowaries, and emus, the fathers carry the task of watching over the eggs and making sure to keep danger away.


Thus, the color of the Heyuannia eggs indicate that the dinosaurs laid eggs in open pits in the ground, and that the fathers were the ones that watched over the eggs. Of course, we can't really be sure of this based on egg fossil evidence alone. However, previous studies have come up with similar findings.


These blue dinosaur eggs may just be the beginning. Wiemann is already planning on finding out if other dinosaurs with open nests also had colored, spotted, or speckled eggs. If she finds eggs like these, we may need to change the way we look at how birds evolved and how dinosaurs behaved.


Hey! Where are you going?? Subscribe!

Get weekly science updates in your inbox!