Early mammals that roamed Earth over 150 million years ago likely sported dark, muted brown fur to evade predators, according to a groundbreaking study by Chinese and Belgian scientists. The research, published in Science, reconstructs the coloration of ancient mammals using fossilized pigments, illuminating their evolutionary adaptation to nocturnal life amid dinosaur dominance.
By analyzing preserved melanosomes—tiny pigment-containing structures—in six Jurassic-era mammal fossils, researchers determined that early mammals had uniformly dark fur. This simple coloration system, distinct from the vibrant hues of feathered dinosaurs, helped them blend into nighttime environments while providing structural strength and heat retention. "The fossils' exceptional preservation allowed us to decode both their ecology and appearance," said Li Quanguo, a co-author from the China University of Geosciences (Beijing).
The findings align with modern nocturnal species like bats, reinforcing theories that mammals evolved nighttime activity to avoid daytime predators. A newly discovered 158.5-million-year-old species highlighted in the study further supports this camouflage strategy. "Dark fur may have been their survival toolkit in a world ruled by dinosaurs," noted Zhou Changfu, a co-author from Shandong University of Science and Technology.
After non-avian dinosaurs vanished, mammals diversified into the spectrum of colors seen today. The study underscores how evolutionary pressures shaped early mammalian traits, offering fresh insights into their rise from shadowy underdogs to dominant life forms.
