Evolution of Mammal Camouflage: A Transition from Uniform Brown to Vibrant Colors

Recent research has revealed that early mammals likely had a much less colorful appearance than previously assumed. Instead of the varied patterns and colors seen in many modern species, these ancient creatures predominantly exhibited a uniform brown coat. This conclusion, drawn from a study published in the journal Science, suggests that the more vibrant coloration of mammals emerged significantly after the extinction of the dinosaurs.

While many dinosaurs are believed to have sported bright feathers and insects likely displayed a wide array of colors, early mammals were probably drab in comparison. According to the international research team, led by experts from the China University of Geosciences in Beijing, mammals around 150 million years ago primarily exhibited dark brown fur, often lacking any distinctive patterns such as stripes or spots.

This coloration is reminiscent of modern nocturnal mammals, including moles, mice, rats, and bats, which utilize such camouflage to blend into their surroundings. The findings support the hypothesis that early mammals were largely nocturnal, a trait that may have helped them evade predation from daytime carnivorous dinosaurs.

The research team examined the structure of pigment organelles, known as melanosomes, in both living and extinct species. These organelles, which store melanin, play a crucial role in determining the coloration of fur, feathers, and skin. Notably, these melanosomes can remain preserved in fossils, allowing scientists to infer the original colors of ancient species.

In earlier studies, researchers established that certain feathered dinosaurs and early birds exhibited vibrant colors. However, the application of this melanosome analysis to fossilized mammals had been limited until now. Utilizing advanced techniques such as scanning electron microscopy, the researchers investigated well-preserved mammal fossils and found evidence supporting the theory of uniformly dark fur.

This nocturnal lifestyle likely provided early mammals a survival advantage, enabling them to avoid detection by day-active predators. Following the mass extinction event 66 million years ago, which saw the demise of the dinosaurs and numerous other species, mammals rapidly filled ecological niches that became available. This shift may have spurred the diversification of fur coloration among mammals as they adapted to new environments.