Recent research has shed light on the coloration of ancient mammals during the Age of Dinosaurs, revealing a prevalence of dark, monochrome coats that helped these creatures blend into their nighttime environments and evade predators. While modern mammals exhibit a diverse array of fur colors and patterns, early mammals and their relatives seemed to be limited to dark grays and browns. This discovery was made by analyzing melanosomes in the hairs of 116 modern mammals, which were then compared to those found in fossilized hairs of six early mammals that lived around 120 million to 167 million years ago in China, during the Jurassic Period. The study found that these ancient mammals likely all had uniformly dark fur.
The shapes and sizes of melanosomes have been linked to the colors they produce in modern mammals, with rounder melanosomes producing brighter colors such as reds and oranges, while elongated melanosomes are associated with blacks and browns. By applying this predictive model to the melanosomes found in the preserved hairs of early mammals, researchers were able to determine that these ancient creatures likely had dark gray or brown fur overall. Despite the various ecological roles of these Mesozoic mammals, from gliders to burrowers, the study suggests that a nocturnal lifestyle and dark fur were common traits among these creatures.
The presence of dark, melanin-rich fur in early mammals may have served multiple purposes, such as aiding in thermoregulation by heating up easily and providing protection to the skin. The study’s findings provide evidence of an anti-predation strategy among early mammals, suggesting that these creatures relied on camouflaging themselves to survive in a world dominated by predators. While the study was limited to six extinct species, it hints at the possibility of discovering patterns or bright colors in other early mammals, should new fossil evidence emerge.
The extinction of nonavian dinosaurs around 66 million years ago may have played a role in triggering a broader spectrum of colors in mammals, as their diversification in response to the disappearance of dinosaurs could have led to a wider range of habitats and niches. Further research could provide insights into when different coloration patterns first arose in mammals and whether ecological factors influenced the development of colorful fur. Sampling melanosomes from mammals that lived during the late Cretaceous Period is suggested as a valuable next step to understand the evolution of fur coloration in ancient mammals.
Overall, this study underscores the importance of modern analytical techniques in paleontology and emphasizes the need for further research to uncover the complexities of ancient mammal evolution. By analyzing the melanosomes present in fossilized hairs, researchers are able to reconstruct the coloration of early mammals and gain insights into their adaptation strategies and lifestyles during the Mesozoic Era.
