Hue times two: a second look at the color of dinosaur eggs


After attracting world attention last year to her research on the egg-colored origins of birds, Yale paleontologist Jasmina Wiemann took a second look at her eggshells.

Wiemann had discovered that all the colors and spots on the eggs of modern birds derived from a single evolutionary source among the dinosaurs. Part of the discovery came from an analysis of pigments found in 18 dinosaur fossil shell samples from around the world. The Wiemann team tested the presence of two eggshell pigments and found them in eggshells belonging to Eumaniraptoran dinosaurs, which include small carnivorous dinosaurs such as Velociraptor.

But a lingering question within the scientific community had to do with whether the pigments found in the eggshells of dinosaurs actually meant that the eggs looked different to the naked eye. A certain level of pigment may have existed in the chemical composition of the shells, without manifesting itself in the external color of the eggs, observers observed.

A new follow-up study published the week of June 20 in the journal Nature indicates that Wiemann's initial conclusion was correct.

"We have demonstrated that our analytical approach really targets egg color and not just egg pigmentation, since we need substantial concentrations of the red pigment, protoporphyrin, to induce a positive signal for the color of the egg," Wiemann said. "The result is the same. The color of the egg had a unique evolutionary origin in the eumaniraptoranos".

An earlier study by a different research team analyzed the pigmentation in the eggshells of Siamese crocodiles. This study speculated that the pigmentation, but not the color of the eggs, may have originated with the archosaurs (a group that includes dinosaurs, birds and crocodiles).

"We have had the opportunity to directly address your question and test – thanks to the Yale Peabody Museum of Natural History egg collection – if there is, in fact, evidence for the red pigment on Siamese crocodile egg shells," Wiemann said. "We have shown that there are no detectable amounts of protoporphyrin in the eggshells of Siamese crocodiles."

/ University Launching. See in full here.


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