Dinosaurs may have given birds their mottled and colored eggs | Smart News

Bird eggs come in a multitude of beautiful colors and patterns, including the whirlwinds of coffee-colored prinia eggs, the dark green emu eggs, and the brilliant blue eggs laid by humble Robin. Scientists have long believed that this variation in eggshell appearance has evolved relatively recently in modern birds, as crocodiles, the closest living relatives of our feathered friends, lay completely white eggs. But like James Gorman of New York Times According to recent reports, a new study found that colored eggs may have appeared in the dinosaur era.

In spite of their diversity, the bird eggs derive their color from only two pigments: protoporphyrin, which produces a reddish-brown color, and biliverdin, which creates blue and green. Last year, a team led by Yale Paleontologist, Jasmina Wiemann, discovered these two pigments in the fossilized eggs of an oviraptor, a small bird-like dinosaur. As part of a new study, recently published in the journal Nature, Wiemann and his colleagues expanded their research to include the eggshells of 15 Cretaceous dinosaurs and extinct birds, as well as live bird eggs such as chickens, emus and terns, reports John Pickrell of Science.

Researchers used a non-destructive technique, Raman microspectroscopy, to bounce lasers off eggshells to map their molecular composition. The team detected the pigmentation of protoporphyrin IX and biliverdin5 in the eggs of modern birds and eumaniraptoran dinosaurs, including the Velociraptor ancestors of the birds of the time. In addition, researchers found that eggs of eumaniraptorane were stained and speckled. The pigments have even been found at the same depth as modern bird eggs on the surface of the shell.

"We have, most likely, only one evolutionary origin of the color of the egg," says Wiemann NPRNell Greenfieldboyce.

Specifically, Wiemann thinks that the color of the egg has evolved as some dinosaurs began to build open nests instead of burying their eggs. The colors and patterns may have helped camouflage newly exposed eggs to predators, or allowed parents to recognize their offspring soon hatched, as is supposed for modern bird eggs. In fact, nesting birds in confined spaces, such as owls and woodpeckers, tend to have white eggs. Some dinosaur eggs analyzed in the study, such as those of some sauropods and the duckbilled dinosaur Maiasauradid not show any pigment, suggesting that these species continued to bury their eggs in the soil.

The new study suggests that there are good reasons to rethink old ideas about the evolution of eggs, but the results of the research are not totally surprising. After all, birds have inherited other traits from their ancestors.

The author of the studies, Mark Norell, explains: "Like feathers and triangles, we now know that the color of the egg has evolved in their predecessors of dinosaurs long before the appearance of birds.

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