According to a new study published Wednesday in the journal Nature, non-bird dinosaurs laid eggs in open or partially open nests. Two, some parent birds use spot patterns to recognize their own eggs if they live in large colonies (or to prevent freeloading birds, like cuckoos, from sneaking their eggs into a brood). So she and some colleagues studied 66-million-year-old egg fossils, searching for the two pigments - a red one and a blue one - that are known to mix and match in bird eggs, creating all of the attractive colors.
Birds, unusual as it seems, are living dinosaurs, the last of a lineage that otherwise went extinct 66 million years ago.
"Some were uniformly colored", said paleontologist and study co-author Mark Norell of the American Museum of Natural History in NY.
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.
"The discovery of a single origin of eggshell color in dinosaurs is a wonderful reminder that modern birds inherited many traits from their dinosaurian ancestors", said Mary Caswell Stoddard, a Princeton University evolutionary biologist who was not involved with this research.
The team found fossil eggs of many colors and speckling patterns. The method requires no destruction of fossils, instead bouncing a laser off the surface of the eggshells to betray their molecular makeup, including whether they carried traces of the two pigments known to color modern eggshells.
"Our study fundamentally changes our understanding of egg color evolution, and adds color to dinosaur nests in the real "Jurassic World".
The evolutionary link between dinosaurs and birds has been recognized for centuries but ornithologists long believed that birds evolved their colored eggs several times over history, mimicking local hues to help their eggs blend in. The biliverdin was able to find in the remains of eggs of seven different dinosaurs. Scientists used to think colored egg shells evolved with modern birds.
At this point, the idea that birds are actually just what's left of dinosaurs is widely accepted, so it should be no surprise that researchers are working hard to determine what pieces of modern birds are actually leftovers from much more ferocious beasts that roamed the earth tens of millions of years back.
So listen well, crayon manufacturers and paint mixers: Robin egg blue is fine, but oviraptor blue is the original.
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.
Though most of us are familiar with blue-speckled robin's eggs or golden-brown chicken eggs, the sheer range of colors and patterns on bird eggs is unbelievable: they can be brick-red, marbled in patterns that look like the surface of the Moon, or covered in squiggly lines like a Jackson Pollock painting. Given the analytical methods from other scientific disciplines now available for work on fossils, "It's an incredible time to be a paleontologist", she says.