New fossil brings us a step closer to unravelling the mystery of feather evolution

By Zixiao Yang, Maria McNamara, University College Cork

Strong but light, beautiful and precisely structured, feathers are the most complex skin appendage that ever evolved in vertebrates. Despite the fact humans have been playing with feathers since prehistory, there’s still a lot we don’t understand about them.

Our new study found that some of the first animals with feathers also had scaly skin like reptiles.

Following the debut of the first feathered dinosaur, Sinosauropteryx prima, in 1996, a surge of discoveries has painted an ever more interesting picture of feather evolution.

We now know that many dinosaurs and their flying cousins, the pterosaurs, had feathers. Feathers came in more shapes in the past – for example, ribbon-like feathers with expanded tips were found in dinosaurs and extinct birds but not in modern birds. Only some ancient feather types are inherited by birds today.

Paleobiologists have also learnt that early feathers were not made for flying. Fossils of early feathers had simple structures and sparse distributions on the body, so they may have been for display or tactile sensing. Pterosaur fossils suggest they may have played a role in thermoregulation and in colour patterning.

Fascinating as these fossils are, ancient plumage tells only part of the story of feather evolution. The rest of the action happened in the skin.

The skin of birds today is soft and evolved for the support, control, growth and pigmentation of feathers, unlike the scaly skin of reptiles.

Fossils of dinosaur skin are more common than you think. To date, however, only a handful of dinosaur skin fossils have been examined on a microscopic level. These studies, for example a 2018 study of four fossils with preserved skin, showed that the skin of early birds and their close dinosaur relatives (the coelurosaurs) was already very much like the skin of birds today. Bird-like skin evolved before bird-like dinosaurs came around.

So to understand how bird-like skin evolved, we need to study the dinosaurs that branched off earlier in the evolutionary tree.

Read Full Story https://theconversation.com/new-fossil-brings-us-a-step-closer-to-unravelling-the-mystery-of-feather-evolution-230058