Multiple origins of avian flight

A newly described Late Jurassic avialan, Yuezhuornis yangyuanensis, has heavy terrestrial adaptations (short wings, teeth, predatory foot) despite placement inside Avialae. This raises the concrete possibility that powered flight either evolved more than once among early bird lineages or was lost repeatedly in some branches. — If flight evolved multiple times (or was frequently lost), it changes how scientists and the public interpret major evolutionary transitions and the contingency vs inevitability of complex traits.