A large enantiornithine bird from the Lower Cretaceous of China and its implication for lung ventilation

Abstract

The Enantiornithes were the most taxonomically diverse bird group in the Mesozoic. Most of the known taxa are from Lower Cretaceous deposits of the Jehol Group in north-eastern China. A new specimen from the Jiufotang Formation in Jianchang, Liaoning Province, is described here; being a subadult individual at the time of death it had reached a relatively large size. The presence of uncinate processes, bicapitate and forked vertebral ribs, sternal ribs that were all of similar length, as well as the location of parapophyses and diapophyses on the thoracic vertebrae, may imply a rigid and volume-constant lung, and less efficient lung ventilation in enantiornithines.

The effect of long-term atmospheric changes on the macroevolution of birds

“…Regarding birds (=Aves), there is an overwhelming consensus that avian evolutionary history was profoundly influenced by a series of key events related to the attainment of powered flight (Sereno and Rao, 1992;Gatesy and Dial, 1996;Padian and Chiappe, 1998;Dial et al 2003;Chiappe, 2007;Heers and Dial 2012;Zhang et al, 2014;Feo et al, 2015;Brusatte, 2015). However, in spite of the potential impact of past atmospheric conditions on flight performance, inferences about the aerial locomotion of extinct birds have largely ignored these aspects, with only a few recent exceptions (e.g., Serrano andChiappe 2017, Serrano et al 2018).…”