Published: Fri, November 02, 2018
Research | By Raquel Erickson

Modern Birds Inherited Colored Eggs from Their Dinosaur Ancestors, Study Says | Paleontology

Modern Birds Inherited Colored Eggs from Their Dinosaur Ancestors, Study Says | Paleontology

"So there are all the functions that are associated with spotting patterns on eggs that we did not even consider for dinosaur eggs". In particular, Jasmine Wiman (Jasmina Wiemann) and her colleagues have discovered a fossilized egg of the oviraptorid age of 70 million years, the biliverdin is a pigment that makes them blue-green color. A new analysis finds that egg color seems to have evolved only once, and that birds maintain this trait from their theropod days.

In spite of their diversity, bird eggs derive their color from just two pigments: protoporphyrin, which produces a reddish-brown color, and biliverdin, which creates blue and green.

Co-author Mark Norell, the Macaulay Curator of Paleontology at the American Museum of Natural History, noted that "Colored eggs have been considered a unique bird characteristic for over a century".

Study author Jasmina Wiemann, now a doctoral student at Yale University, began her search for colorful eggs with a dinosaur named Heyuannia huangi, an oviraptor with a beak like a parrot's.


Bird eggs come in a host of attractive colors and patterns, including the coffee-colored swirls of prinia eggs, the deep green of emu eggs, and the brilliant blue of the eggs laid by the humble robin. That study raised a question about whether the colors of bird eggs can be traced to a dinosaur origin or if they evolved on their own.

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. Pigment did not occur in the crocodilian, sauropod, or ornithischian eggs (the other two dinosaur groups), according to the study published in Nature.

People who are accustomed to see the eggs alone the hen, it is hard to imagine how diverse is their colouring from other birds, from chocolate brown to emerald green, from brick red to bright blue. They all belong to the group of Eumaniraptora, which will include modern birds. One animal coloration expert not involved in the study, professor Mary Caswell Stoddard at Princeton, thought the research would ignite conversations about dinosaur behavior. "We tried to cover the major branches of dinosaurs to get a good idea for all non-avian dinosaurs", she says.

Egg colour provided a massive advantage to dinosaurs that had exposed nests for their eggs, rather than burying them into the ground similar to that of turtles and alligators, with a view of providing camouflage to protect against egg-eating predators, the researchers said. The researchers will now need a larger sample of eggshells to analyze. A relative of Velociraptor called Deinonychus laid eggs with blue-green color; the lightly built carnivorous troodontids had eggshells of blue-green, beige, or white; and the eggs of the Chinese oviraptorosaur Heyuannia previously tested were deep blue-green. Before this work, though, many biologists predicted that modern birds, not their ancestors, developed colorful eggshells. And the presence of speckling raises the possibility there may have been nest parasites long before the appearance of birds - the cuckoo dinosaur.

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