Researchers have uncovered the coloration of some of the earliest mammals that lived during the Mesozoic era, a period when dinosaurs ruled. The study, published in Science today, reveals that these early mammals had dark brown or grayish fur, unlike the grayish, scaly monsters often depicted in movies.
The discovery reinforces the idea that mammals “lived in the shadow of the dinosaurs” and likely lived nocturnal lifestyles to avoid unwanted attention. To reconstruct the color of ancient creatures, scientists look for fossils that preserve melanosomes – intracellular structures containing pigment melanin. The study analyzed six fossil species, including a previously undescribed ancient mammal found in northeastern China.
The researchers created a database of modern mammals’ hair colors and melanosome shapes to develop a model predicting hair color from melanosome shape. They found that the medium-sized creature, named Arboroharamiya fuscus, had oval-shaped melanosomes that predicted its dark brown fur color.
Fluorescence imaging revealed high concentrations of copper in the fossils, associated with eumelanin, which produces blacks and browns. The study suggests that these mammals were not only darkly colored but also lacked patterns, unlike modern nocturnal mammals.
The findings support researchers’ long-held suspicion that Mesozoic mammals were mostly nocturnal to avoid giant dinosaurs. The dark fur may have helped creatures regulate body temperature by absorbing more light and heat at night.
Future studies aim to explore how fur color changed in mammals after the dinosaurs went extinct 66 million years ago, potentially revealing the relationship between fur color and metabolism.
Source: https://www.science.org/content/article/dinosaur-era-mammals-fur-color-revealed-first-time