Dinosaur eggs had the blues.
Pigments detected in 66-million-year-old eggs from China suggest that the shells came in intense shades of bluish-green, scientists report online May 15 in PeerJ Preprints. Picking up on eggshell pigments could help scientists color in the details of dinosaurs’ nesting habits.
“This is very, very cool,” says paleontologist Luis Chiappe of the Natural History Museum of Los Angeles County. The authors’ approach “allows you to reconstruct the original color of dinosaur eggs.” No one has tried this before, he says.
Scientists have previously inspected dinosaur fossils for hints of color: Ancient feathers may have glimmered iridescent or flashed shades of auburn and chestnut. But no one had a clue about eggshell hues, says study coauthor Martin Sander, a paleobiologist from the University of Bonn in Germany.
Sander, Jasmina Wiemann and other Bonn colleagues thought fossilized shells might harbor remnants of color, too. The pigments that stain chicken eggs reddish-brown and robin eggs vivid blue are chemically stable molecules, Wiemann says. So any pigments in dino eggs might not have crumbled away completely over time. To find out, she analyzed shell slivers from fossilized eggs collected at three sites across eastern China.
The eggs, stretched-out orbs about the length of Coke bottles, belonged to Heyuannia huangi, a short-beaked, crested dinosaur that looked kind of like a little emu. With mass spectrometry, Wiemann detected preserved pigments in different layers of the dinosaur’s eggshells. These pigments could have dyed the eggs a spectrum of shades, from deep olive to brown-speckled blue.
The bluish color may have helped camouflage eggs laid in open nests, the authors suggest. It also hints that dino dads helped out with egg care. Modern birds that lay blue-green eggs tend to rely on fathers to tend the nest, Wiemann says.
The similarity between dinosaur and bird eggshells is what’s neat, Chiappe says. “It’s another line of evidence that supports the idea that birds are living dinosaurs.”