An article published in the journal “Nature Ecology & Evolution” reports the discovery of two specimens of pterosaur that lived in today’s China about 165-160 million years ago, during the Jurassic period, that had filaments called pycnofibres that make up a plumage. A team of researchers studied under the microscope those pycnofibres finding four different types of feathers, concluding that they’re very similar to those of birds and those found in feathered dinosaur fossils.
Pterosaurs were reptiles and were the first flying vertebrates, already during the era when dinosaurs were still becoming a dominant group and well before some of them started developing the characteristics that would led them to evolve into modern birds. The fact that they had a kind of hair consisting of pycnofibres was known but the available fossils suggested that they were simple filaments, very different from the complex ones typical of feathered dinosaurs and birds. The study of very well preserved pterosaur fossils discovered in Mongolia and belonging to what’s called Yanliao Biota may point to a different story.
Baoyu Jiang of Nanjing University, one of the authors of the research, explained that he and his colleagues went to research in the Daohugou Formation, Mongolia, because they knew that in the area excellent specimens of pterosaurs were already found with their pycnofibres well preserved. Their search was successful with the discovery of two specimens in excellent condition.
The researchers examined the two pterosaur specimens with a scanning electron microscope (SEM) in order to obtain high quality details of their pycnofibres, discovering that they were of different types. The simple filament type – basically hairs – already known, was only a part of the filaments but there were also filament structures and above all two types that have typical characteristics of feathers such as a tuft structure and even more tufts filaments that start from various areas of a larger filament.
Zixiao Yang, also from the Nanjing University, another author of this research, explained that he was able to examine all parts of the specimens under a microscope. This allowed him and his colleagues to find many examples of all four types of pycnofibres.
A further discovery that contributed to the conclusion about the nature of those pycnofibres similar to those of birds and feathered dinosaurs is that of melanosomes, cells that produce melanin. In the case of these pterosaurs, that pigment had to have a ginger color. Again, it’s a characteristics quite similar to that of birds and feathered dinosaurs.
The characteristics discovered in the plumage of pterosaurs make it difficult to think that there was a parallel evolution in dinosaurs. It seems much more likely that those characteristics were inherited from common ancestors and that in some groups of animals they turned into hairs, as in mammals.
Michael J. Benton of the British University of Bristol, another author of the research, stressed the importance of these discoveries for our understanding of the origins of feathers but also regarding an important period for the evolution of life on the mainland. In fact, it suggests that some kind of plumage evolved around 250 million years ago, when life forms were recovering from the devastating extinction of the end of the Permian.
This is one of the cases in which the discovery of fossils in an excellent state of conservation and exams that exploit modern technologies can provide very important results for palaeontologists. The evolution of plumage is linked to that of metabolism in warm-blooded organisms with a number of consequences on their diet and their life so it can definitely change our understanding of the lives of many animals.