Israeli Scientists Find Earliest Evidence of Bird Feather Molt in Flying Dinosaur

By: TPS Staff

A unique study conducted at the University of Haifa has, for the first time, documented the common process of sequential feather replacement found among modern birds in a winged dinosaur dating back 120 million years.

The finding shows that the dinosaur had highly-develop aerodynamic properties and may have lived in a habitat in which it faced predation risk or that it needed to maintain its flight capacities during molting.

“It is fascinating to see how a mechanism that began to develop at least 120 million years ago also exist in today’s birds,” said doctoral student Yosef Kiat of the Animal Flight Laboratory in the Department of Evolutionary and Environmental Biology at the University of Haifa, who led the study.

“It is also fascinating to see how we can use our modern knowledge about this mechanism in order to yield insights into the evolution and ecology of a dinosaur that lived 120 million years ago,” he added.

Birds must molt and replace their feathers periodically in order to maintain their proper functioning. Once a feather reaches its full size it becomes a dead organ; the bird must then shed the old feather and sprout a new one in its place to ensure that its plumage remains functional for flying and other functions.

The molting strategy may indicate an ability to fly and provide clues about birds’ habitat. In species that spend much of their time in flight or in habitats exposed to predators, such as open areas with sparse vegetation that do not provide hiding places from predators, molting takes place in a gradual, sequential and slow manner in order to ensure that the birds maintain their flying capabilities even during the molting process.

In birds that do not fly often, or that have access to numerous hiding places from predators without needing to fly, the process can be very rapid and the bird sheds a large number of feathers simultaneously and the entire molting process takes just two to three weeks.

The team took this knowledge and sought to apply it to the Microraptor, a dinosaur that lived 130-120 million years ago and whose fossil found in China unusually retained the fossilized marks of its wing feathers.

“Naturally it’s by no means a routine matter to find a relatively complete dinosaur fossil, but it’s even rarer to find well-preserved fossilized wings. The feathers do not usually survive the fossilization process, but in this particular case most of the wing feathers can be seen very well,” Kiat explained.

After the researchers arrived in China, they methodically examined the fossil in order to determine whether there was any evidence of molting.

“At first glance, six feathers of differing sizes can be seen. However, we had to see whether we could be certain that these really are feathers of different lengths that are part of the molting process, rather than a feather that broke or was shortened for some reason. After some hard work, we managed to identify the borders of the feathers and to confirm that we were indeed looking at a wing that has feathers of several different lengths in a sequence. In other words, the Microraptor replaced its feathers in a gradual manner,” the researchers explained.

(TPS)