Early mammal fur revealed through fossils

Animals that lived in the distant past seemed to appear impossible. However, since the 1990s, thousands of fossils have been discovered with feathers and fur.

In some cases, when these fossils are examined under a microscope, traces of the cellular organelle-melanosome containing the pigment melanin are found.

Melanin comes in two variants, black brown and yellow red, and the shape of the melanosome varies depending on the composition. Therefore, knowing the shape of the melanosomes in the fur and feathers gives you a good idea of ​​their colour.

Shawkey's team began by looking at furry melanosomes in a diverse range of 116 living mammals. From this, the researchers developed a model to predict fur color based on the shape of melanosomes and applied this to six different early mammal fossils.

All six fossils originated from the same deposits in China, but the species lived at various times from the mid-Jurassic to the early Cretaceous period, around 165 million to 120 million years ago. One of them was the newly described name Gliding Mammals Arrives It lived around 159 million years ago.

Given that all of these mammals are thought to have been nocturnal, it is not surprising that they were all rather simple.

“We expected them to have a rather subdued colour,” says Shawkey. “One thing that surprised me was how unchanging they were. The colors were even more similar than I had predicted.”

The team plans to expand the study by examining additional early mammal fossils from elsewhere in the world, but Shokey doesn't believe the results will be significantly different. After the dinosaurs went extinct 66 million years ago, many mammals became active during the day, and perhaps when their colours became more diverse, he says.

Fossils of dinosaurs and marine reptiles contain preserved skin, but few attempts have been made to resolve skin colour from the fossils.