Color evolution: Ginger pigment found in 10-million-year-old frogs

Palaeontologists at University College Cork (UCC) have found molecular evidence of phaeomelanin – the pigment responsible for ginger coloration – in fossilized frogs. 

The study, led by Dr. Tiffany Slater and Professor Maria McNamara, adds a crucial layer to our understanding of ancient animal colors and the evolution of pigments in the animal kingdom.

Focus of the study

“Melanin pigments play a critical role in physiological processes and shaping animal behavior,” wrote the study authors.  

“Fossil melanin is a unique resource for understanding the functional evolution of melanin but the impact of fossilisation on molecular signatures for eumelanin and, especially, phaeomelanin is not fully understood.”

The researchers collaborated with scientists from Fujita Health University (Japan), Linyi University (China), and Lund University (Sweden). 

The team meticulously analyzed 10-million-year-old frog fossils, identifying molecular fragments of phaeomelanin, which is remarkable considering the pigment’s toxicity to contemporary animals.

Exciting discovery 

“This finding is so exciting because it puts palaeontologists in a better place to detect different melanin pigments in many more fossils,” said Dr. Slater. 

“This will paint a more accurate picture of ancient animal color and will answer important questions about the evolution of colours in animals.”

Evolutionary mystery 

Dr. Slater noted that scientists are still unraveling the mysteries of phaeomelanin, seeking to understand how and why this pigment, currently toxic to animals, evolved in the first place. 

The newly discovered fossil evidence could play a pivotal role in solving this mystery. 

Dr. Slater believes that this finding significantly empowers palaeontologists, enabling them to detect various melanin pigments across a broader range of fossils, thus providing more precise insights into the ancient creatures’ coloration and their evolutionary journey.

Fossilization experiments

The experts conducted laboratory experiments on feathers of different colors (black, ginger, and white) to understand how phaeomelanin pigments undergo degradation during the fossilization process. 

“Fossils are invariably altered by the ravages of heat and pressure during burial, but that doesn’t mean that we lose all original biomolecular information,” said Professor McNamara.

“Our fossilization experiments were the key to understanding the chemistry of the fossils, and prove that traces of biomolecules can survive being cooked during the fossilization process.” 

Biochemical evolution

“There is huge potential to explore the biochemical evolution of animals using the fossil record, when we account for chemical changes during fossilization.” 

This discovery by the UCC team marks a significant step forward in palaeontology, promising a richer and more accurate understanding of the color palette of ancient life and the evolutionary history of animal pigments.

The study is published in the journal Nature Communications.

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