Dinosaurs May Have Given Birds Their Colorful, Speckled Eggs

James Marshall
November 3, 2018

According to Wiemann: "This dinosaur is particularly interesting because oviraptors are the first dinosaurs that built open nests.Once you start to build an open nest, your eggs are exposed to the environment". Small corvid eggs surround the larger eggs.

In the eumaniraptorans, the researchers found evidence of a blue-green pigment named biliverdin and a red-brown pigment called protoporphyrin IX structurally integrated into the crystal matrix of the eggshell, as they are with birds. Dinosaur relatives of birds, though, had colorful eggs, including spots and both pigment types.

To find out whether colored dinosaur eggs shared an evolutionary origin with those of birds, Wiemann and her colleagues amassed well-preserved fragments of fossil eggshell from 15 Cretaceous era dinosaurs and extinct birds, as well as eggshell from living chickens, terns, emus, and alligators.

"Some were uniformly colored", said paleontologist and study co-author Mark Norell of the American Museum of Natural History in NY.

An illustration shows a deinonychus chick hatching from a blue egg with brown spots.

Wiesmann, who hopes her study can be used for future research, offered an explanation for how egg colors may have adapted.

A team of researchers has found that "birds inherited their egg color from non-avian dinosaur ancestors that laid eggs in fully or partially open nests", Yale University announced Wednesday. They developed a way to use that technique, known as Raman spectroscopy, to pick out pigments from other molecules.

If you're interested in all the practical advantages of speckled and brightly colored eggs, check out this article. The color, size, and pattern of a bird's eggs is often unique to its species, and there's online tools and even entire books dedicated to classifying bird eggs so that bird watchers can easily identify them.

"This completely changes our understanding of how egg colors evolved", said the study's lead author, Yale paleontologist Jasmina Wiemann.

The evolutionary link between dinosaurs and birds has been recognised for centuries but ornithologists long believed that birds evolved their coloured eggs several times over history, mimicking local hues to help their eggs blend in.

Traditionally, dinosaurs were thought of as reptilian-style breeders that dumped their eggs and left. Crocodiles and turtles bury their white eggs, which means they don't need to be camouflaged. It was just like in living birds.

Most likely, it was a single event, even of uncertain mutation, which caused accumulation of biliverdin in the shell and made the eggs for the beginning of blue-green.

Wiemann plans to increase the dinosaur sample size to see whether she can pin down exactly where and when within the carnivorous theropod group of dinosaurs (which also includes birds) colored eggshells first evolved, and what color came first.

Hauber offered three other reasons, in addition to camouflage, why birds have colorful eggs: One, pigments can act like a parasol or sunscreen, protecting the embryos within from too much heat. Given the analytical methods from other scientific disciplines now available for work on fossils, "It's an wonderful time to be a paleontologist", she says.

Other reports by Click Lancashire

Discuss This Article