Petrified pigment cells can tell us which colors have long had extinct animals such as dinosaurs. Researchers have now applied to six early mammals that lived alongside the dinosaurs 150 million years ago. As it turned out, these primeval animals had all uniformly dark fur, which could be related to their nocturnal lifestyle: the dark fur primarily served the camouflage. On the other hand, today’s variety of colors and patterns under mammals probably only emerged after the dinosaurs died out.
Compared to a few brightly colored birds, fishing and reptiles, the fur of mammals bears a rather muted color palette. This is because there is only one pigment in our pigment cells: the melanin. However, it occurs in two chemical variants: the eumelanin, which generates black and brown tones, and the Phäomelanin, which is responsible for yellow and red tones. Due to the combination of both variants, the fur of mammals can take numerous impressive patterns-from tiger strips to dalmatian points to the black and white of giant pandas.
The colors of our ancestors on the trail
However, the pigments of EU and pheomelanine not only differ in terms of the colors that they produce, but also in the form of their melanosomes- those organelles in pigment cells that form and store melanin. As researchers about Ruoshuang Li from the Chinese University of Geosciences report, melanosomes of orange-red fur are rather spherical, while melanosomes of dark fur are rather elongated. This was confirmed by a scanning electron microscopic and spectrophotometric measurement of 116 mammals living today.
Based on this data record, the team was able to develop a model with which the fur color extinct mammals can also be reconstructed. To do this, the fossil melanosomes must have been preserved as three -dimensional, petrified prints. This is particularly the case with around 150 million years old finds from the northeast of China. The fossil mammals discovered there are sometimes so well preserved that the impressions of their fur can be seen with the naked eye. But what color did they wear? Li and her colleagues have now determined this based on six different species, which once occupied various niches alongside the dinosaurs. Some were lived in the tree, others were probably able to slide and others probably lived underground.
A uniform dark brown
The result: Despite their different way of life, all mammals examined once had a similar fur color to Li and their team. “Samples that were taken from different places of each fossil showed a uniform dark brown color, without signs of color patterns such as stripes, stains or counter -shades, as can be found in today’s mammals,” the researchers write. The lack of variation is probably due to the fact that most of the early mammals were nocturnal at the time of the dinosaurs and helped them an inconspicuous fur for better camouflage. Modern native mammals such as moles, mice, rats and bats are mainly colored.
In addition, the heavily melanized hair could have been other useful to our early mammal ancestors. “Melanization increases the heating speed of materials and darker hair could help small mammals to reduce heat loss through insulation,” explain Li and her colleagues. Because the mammals in the dinosaur era were primarily small and rodent-like, they could have kept their body temperature more stable. “Melanized materials are also more stable and abrasion -resistant, so that the hair may withstand wear and protect and protect the skin,” the scientists call a further advantage.
Sample formation only after the end of the dinosaurs
The team assumes that the mammals only developed their current colors and patterns variety after the dinosaurs extended. When our ancestors occupied the niches freed by the mass extinction around 66 million years ago, some of them were now also active during the day. From then on, her fur was able to serve visual communication with fellow species and in particular sexual selection and no longer had to be unobtrusive, as the researchers explain.
Source: Ruoshuang Li (China University of Geosciences) et al., Science, Doi: 10.1126/science.ads9734