Jackson School of Geosciences professor links spectrum of dinosaur colors to evolution

Justin Atkinson

Research involving the pigmentation of dinosaurs has led researchers at UT to link prehistoric evolution to color.

Julia Clarke, an associate professor in the Jackson School of Geosciences, collaborated with a research team spanning across seven universities to study similarities between living organisms and extinct animals, and found that evolutionary shifts followed changes in the species’ color.

“I’m excited,” Clarke said. “When we started this work we never imagined that trying to figure out aspects of color would lead us to potentially learn something new about dinosaur physiology.”

The research compares the hair, skin and feathers of living terrestrial vertebrates and fossil specimens to find relations in levels of melanin, the pigmented tissue within organisms that determines color, and melanosomes, the organelles that hold melanin.

“Living mammals and birds uniquely show a relationship between the shape of melanosomes and their color — it’s what colors our hair,” Clarke said. “Genes that are involved in melanin-based color are also involved in many other aspects of physiology, like food intake and aspects of reproduction.”

Anthropology professor John Kappelman said the study, which was published in scientific journal “Nature” on Thursday, is expanding the scientific community’s ability to classify the physical characteristics of dinosaurs.

“These results are really exciting because it gives paleontologists one more tool that can be used to study the physiology of extinct species and reconstruct their color,” Kappelman said. “So, unfortunately, Tyrannosaurus rex — while a very colorful character — probably did not have vibrant colors.”

Additionally, the research assists in identifying which dinosaur species were warm-blooded or cold-blooded by comparing similar melanin diversity between living species and extinct specimens, according to integrative biology professor David Cannatella.  

“We know that birds — which are living dinosaurs — are endothermic, or warm-blooded,” Cannatella said. “Whether extinct dinosaurs that are closely related to birds were endothermic or not has been debated for decades, so this work is highly significant as evidence that supports endothermy in this extinct group of dinosaurs.”

Clarke said the study leaves more work ahead to prove their hypothesis linking evolution and color change.

“We are continuing our work in this area,” Clarke said. “We will be looking at more fossils and also hope that more research on the melanin in living vertebrates may also illuminate the hypothesis we’ve put forth.”