An artist’s depiction of the Sapeornis, shown with its leg feathers. Image credit: Yike Xu.

Most feathered dinosaurs have been found in China and among these some the absolutely finest fossils ever found.

Now some Chinese researchers have particularly investigated findings of dinosaurs with feathers in relation to what appears to be the first birds that evolved from dinosaurs and their conclusion is that early birds had four wings.

The researcher argues that this is how birds first evolved flight. And as smaller and more nimble creatures, they had an advantage in the aftermath of the event that caused the dinosaurs to die out.


Since many intermediate forms of dinosaur/birds have been found in China in recent time, these provide us with glimpses of the transformation that dinosaurs underwent when evolving into birds over several millions of years.

China has certainly been the source of many findings of be-winged feathered dinosaurs during the last 20 years and these fossils have led to a revolution in the way we view dinosaurs. As the theory now is that the very first function of feathers was to retain body heat.

Reconstruction of Iberomesornis expuesto at the Museo Nacional de Ciencias Naturales in Madrid, Spain.

Dinosaurs to Birds

That dinosaur species is the genetic ancestors of birds is now an accepted theory. The question remains however how the evolution of wings first got started.

There are two broad theories of how this process took place and both points to necessary biological adaptations. As the first theory is “down from the trees” and the second being “off the ground”.

Down From the Trees

The first theory presents the ancestors to bewinged dinosaurs to have lived in trees. To facilitate faster and easier movement between trees, or from the ground up to trees, to catch prey or escape predators – feathered wings developed to provide a distinct advantage.

These tree living dinosaurs probably gradually evolved viable wings to glide, flutter and eventually fly.

Off the Ground

The off the ground theory presents the idea of fast insect chasing dinosaurs running down their prey. Those dinosaurs with wings had an advantage in chasing down prey, jumping higher and higher, gliding and eventually flying.

Four Wings

The Chinese paleontologist Xing Xu who led a team at the Institute of Geology and Paleontology in Shandong examined a bird-like dinosaur with well-developed wings on four legs.

The result of this research has been published in this week’s issue of Science. Presenting a total of eleven species of early birds, all found within the same area in northeastern China and all about 125 million years old.

The hind springs are clearly noticeable in some of the species and Xu argues that the rear wings may have had an importance for the ability to fly, for lifting off the ground or to easier control flight.

These early birds had a disadvantage in body composition compared to modern birds, for which evolution has made both lighter and more efficient flyers.

With more findings to come, we are slowly gaining a complete picture of how the evolution of birds from dinosaurs took place.

Hind Wings in Basal Birds and the Evolution of Leg Feathers