Its elaborate tail feathers appear to contain a mix of functional and decorative characteristics, scientists say, revealing new insights into the evolution of ancient birds.

Research published today in Current Biology describes Yuanchuavis, an early Cretaceous bird with a pair of tail feathers longer than its body.

“The pintail is a tail shape that is shaped by both natural and sexual selection, and it serves both purposes: increased chances of both survival and reproduction,” said O’Connor.

“The tail fan provides lift to help during flight while the two elongated tail feathers are ornaments that can be used to attract mates.”.

Then the feathers create drag making it harder to fly so more energy is needed to move around.” It cost the bird a lot to have the two long feathers, she said, and they were not something that increased its chances of survival.

Michael Pittman, a vertebrate paleontologist at the University of Hong Kong who wasn’t involved in the research, said it’s entirely possible that sexual selection resulted in the elongated feathers, but that “knowledge gaps” still exist in this area.

That said, Pittman said the new study “paves the way for a clearer understanding of early tail feather evolution that leverages what we already know about modern birds, where we can see the tail feathers themselves but we can also directly observe how the tail feathers are used.’’.

The notion that sexual selection shaped the tail feathers of Cretaceous birds is nothing new, Dennis Voeten, a paleontologist at Uppsala University and an expert on ancient birds, explained in an email.