Two new discoveries of the feathered dinosaur Similicaudipteryx have shown dramatic changes in the plumage that could only mean that the dinosaur moulted as it grew.  Both of these well-preserved specimens are juveniles but of differing ages. In the larger and therefore older of the two fossils the long feathers on the tail and forelimbs are very similar to modern day birds. However in the smaller and younger dinosaur these feathers are only similar at the ends whilst the section of the feather near the body is ribbon-like.

Similicaudipteryx obviously changed the structure of its feathers whilst a juvenile. This would have been achieved by moulting its original feathers so that new ones could be grown, and may well be related to a specific pattern of gene activity. The research team was lead by Xing Xu in Bejing. Similicaudipteryx lived 125 million years ago in the early Cretaceous period in what is now China.