A priori, to our imaginations fueled by fictions like Jurassic Park , there can be no two creatures more different than a hummingbird and a dinosaur. But the last fossil of theropod – a suborder of animals whose only living descendants are birds – found in northwest China, according to the authors of the find, reminds that graceful bird: its plumage has nothing to do with what had been seen so far in the fauna of 160 million years ago . The study has been published in the journal Nature Communications .
Baptized as Caihong juji (“rainbow with a great crest”, in Mandarin language), the new prehistoric species was about the size of a duck and, as can be seen from the analysis, iridescent feathers that change color according to the sunlight. . This striking characteristic is shared by several modern birds, and it has been deduced thanks to the excellent state of preservation of the fossil. “Although I have seen many feathered dinosaurs before, I have been struck by the beautifully preserved feathers of this specimen,” said Xing Xu, a paleontologist at the Chinese Academy of Sciences and one of the study’s authors.
An iridescent display
Specifically, experts have examined the remains of cells identified as melanosomes with an electron microscope in 66 body locations, which contain melanin, a substance responsible for pigmentation in animals and for which we become brown. Thus, they verified that the melanosomes of the head, chest and certain parts of the dinosaur’s tail formed a kind of sheet, as occurs with current hummingbirds. In the case of these birds, it gives their feathers a metallic shine and allows them to break down the light like a prism. However, paleontologists warn that additional chemical studies are needed to confirm that it is indeed melanosomes, and not, for example, bacteria, which would invalidate their hypothesis. If confirmed, the costume would have social or sexual functions, to demonstrate status or attract potential partners, although at the moment its exact evolutionary origin is unknown.
Caihong juji lived in forests, where it fed on lizards and small mammals. In addition to its plumage, it also sported a bony crest in the middle of a skull reminiscent of the probably also feathered velociraptors. Another striking feature is the asymmetry of the tail feathers, an indication that it was pre-adapted for flight, which would make our “rainbow dinosaur” the oldest animal with this feature.
Illustration: Velizar Simeonovski / The Field Museum
Source: Nature Communications 9, Article number: 217 (2018)
doi: 10.1038 / s41467-017-02515-y
