Non-avian dinosaurs may have had bright color on their skin, scales and beaks in a manner similar to modern birds, according to a paper published in the journal Evolution.
A simplified evolutionary tree showing where bright colors appear on birds and other living species from the study and where these colors may have appeared on their extinct relatives, including dinosaurs; skin (shown in orange), and scales and beak keratin (yellow) could have been brightly pigmented in extinct groups, whereas feathers and claws would probably not have been; areas without bright color are shown in gray. Image credit: Sarah Davis / University of Texas at Austin.
“Living birds use an array of pigments and can be very colorful on their beaks, legs, and around their eyes,” said study’s lead author Sarah Davis, a doctoral candidate with the Jackson School of Geosciences at the University of Texas at Austin.
“We could expect that extinct dinosaurs expressed the same colors.”
The takeaway on potential dinosaur color schemes comes from broader findings about skin and tissue color in the most recent common ancestor of living birds and extinct dinosaurs.
By analyzing whether bright body color was present in living dinosaur relatives (turtles, crocodiles and over 4,000 bird species), Davis and her colleague, University of Texas at Austin’s Professor Julia Clarke, determined that the common ancestor had a 50% chance of having bright colors in the soft tissues of its body.
The bright colors examined in the study typically come from carotenoids, a class of colorful red, orange and yellow pigments that birds extract from their food.
Carotenoids do not fossilize as well as brown and black pigments, which means scientists must study color in living animals to look for clues about color expression in their extinct ancestors.
Davis and Professor Clarke used the data collected from birds and other animals to make phylogenic reconstructions, a scientific method used to investigate the evolutionary histories of species.
The 50% estimate for bright color applies equally to skin, beaks and scales of the ancient archosaur.
“In contrast, we found that there was a 0% chance that claws and feathers were brightly colored, which is consistent with other research,” Davis said.
The authors also examined the connection between color and a diet high in carotenoids.
They found that birds with higher carotenoid diets (plant- and invertebrate-rich) were more likely to be colorful than meat eaters.
What’s more, they found that plant-eating birds expressed bright colors in more places on their bodies than meat eaters or omnivores.
“The earliest dinosaurs were pony-sized and ate large, vertebrate prey,” Professor Clarke said.
“Different groups shifted to plant-dominated or mixed diets. This shift likely led to changes in coloration of skin and non-feather tissues.”
_____
Sarah N. Davis & Julia A. Clarke. Estimating the distribution of carotenoid coloration in skin and integumentary structures of birds and extinct dinosaurs. Evolution, published online October 31, 2021; doi: 10.1111/evo.14393
Source link: https://www.sci.news/paleontology/dinosaur-carotenoid-coloration-10354.html
