Praeornis sharovi Rautian, 1978 a fossil feather from the early Late Jurassic of Kazakhstan

Abstract

Since its original description as a feather belonging to a basal bird, the phylogenetic position of Praeornis sharovi was debated. It was considered as belonging to a bird, a cycad leaf, or as a ‘transitional’ integumentary structure between reptile scales and bird feathers. Recently, a basal enantiornithine bird was collected in Early Cretaceous beds of Brazil. This specimen shows very well-preserved rachis-dominated tail feathers with a very thick rachis and thick and rigid barbules. These features are present in Praeornis, suggesting that this fossil may be interpreted as the tail feather of a basal bird. In this way, Praeornis constitutes one of the oldest records of rachis-dominated feathers in the world. Rachis-dominated tail feathers, including that of Praeornis appear to be rigid paired structures not performed for aerodynamical purposes, suggesting that may be important in body balance.