Dark fur helped early mammals evade predators: study

BEIJING -- The early mammals that lived alongside dinosaurs over 150 million years ago likely had dark, dusky brown fur, helping them blend into the night and evade predators.

A collaborative team of Chinese and Belgian scientists has reconstructed the coloration of Earth's earliest mammals using fossilized pigments, offering new insights into their secretive nocturnal lifestyles and evolutionary strategies.

The study, published Friday in the journal Science, suggests that early mammals relied on a simple melanin-based system, producing muted tones ideal for nocturnal camouflage.

This adaptation aligns with modern nocturnal mammals like moles and bats, reinforcing theories that our mammal ancestors evolved nighttime activity to evade daytime predators.

This stands in stark contrast to the varied colors found in feathered dinosaurs and early birds, indicating a distinct evolutionary pattern for mammalian coloration, according to the study.

"These extinct early mammals had distinct lifestyles, ranging from ground-dwelling and burrowing to gliding through the treetops like modern-day flying squirrels," Li Ruoshuang, the paper's first author from the China University of Geosciences (Beijing), told Xinhua.

"The incredible preservation of the fossils and their fur impressions enabled us to piece together both their ecology and their coloration," said Li Quanguo, the paper's corresponding author from the same university.

The researchers analyzed fossilized pigments, known as melanosomes, to determine the fur color of six ancient mammal relatives, including a newly discovered species from 158.5 million years ago in the Late Jurassic.

By analyzing melanosome shapes in 116 living mammals, the team created a model linking structure to color, finding that the humble ancestors of modern mammals had solid dark fur without patterns.

"This dark color may have helped them hide from dinosaurs," said Zhou Changfu, a co-author from Shandong University of Science and Technology.

Aside from camouflage, dense melanosomes in their fur likely aided heat retention and strengthened hair structure for protection, according to the study.

After the extinction of non-avian dinosaurs, mammals may have been free to diversify into the wide array of colors, from orange tamarins to grey koalas and black-and-white patterns of zebras, according to the researchers.