New Bohaiornis-like bird from the Early Cretaceous of China: enantiornithine interrelationships and flight performance.

Luis M. Chiappe,Francisco Serrano,Trond Sigurdsen,Meng Qingjin,Wang Min,Liu Di,Alyssa Bell

doi:10.7717/peerj.7846

Abstract

During the last decade, several Bohaiornis-like enantiornithine species—and numerous specimens—have been recognized from the celebrated Jehol Biota of northwestern China. In this paper, we describe the anatomy of another “bohaiornithid” species from the 125 million-year-old Yixian Formation of Liaoning Province, China. The new taxon differs from previously recognized “bohaiornithids” on a number of characters from the forelimb and shoulder girdle. We also provide a new phylogenetic framework for enantiornithine birds, which questions the monophyly of the previously recognized bohaiornithid clade and highlights ongoing challenges for resolving enantiornithine interrelationships. Additionally, we offer the first assessment of the flight properties of Bohaiornis-like enantiornithines. Our results indicate that while “bohaiornithids” were morphologically suited for flying through continuous flapping, they would have been unable to sustain prolonged flights. Such findings expand the flight strategies previously known for enantiornithines and other early birds.

Highlights

During the last three decades, the celebrated Early Cretaceous Jehol Biota of north-eastern China has yielded a rich fauna of enantiornithines (Sereno & Rao, 1992; Zhou, Jin & Zhang, 1992; Zhou, 2002; Hou et al, 2004; Chiappe, Ji & Ji, 2007; Zhou, Clarke & Zhang, 2008; O’Connor et al, 2009, 2011, 2016; Chiappe & Meng, 2016), a diverse clade of Cretaceous birds known worldwide (Chiappe & Walker, 2002)
We describe the anatomy of a new Bohaiornis-like taxon from the 125 million-year-old Yixian Formation (Fig. 1)
The identification of BMNH Ph 829 as an enantiornithine is supported by the presence of characters that are consistently interpreted as synapomorphies of this clade: thoracic vertebrae bearing centrally located parapophyses, a Y-shaped furcula with laterally excavated rami, a radius that bears a longitudinal groove on its interosseous surface, a femur with a prominent posterior trochanter on its proximolateral margin, a relatively thin metatarsal IV, and a long metacarpal III that projects more distally than metacarpal II (Chiappe & Walker, 2002)

Summary

Introduction

During the last three decades, the celebrated Early Cretaceous Jehol Biota of north-eastern China has yielded a rich fauna of enantiornithines (Sereno & Rao, 1992; Zhou, Jin & Zhang, 1992; Zhou, 2002; Hou et al, 2004; Chiappe, Ji & Ji, 2007; Zhou, Clarke & Zhang, 2008; O’Connor et al, 2009, 2011, 2016; Chiappe & Meng, 2016), a diverse clade of Cretaceous birds known worldwide (Chiappe & Walker, 2002). Despite the fact that the interrelationships of these extinct birds continue to be contentious, recent studies have identified a number of distinct Jehol clades including Pengornithidae (Zhou, Clarke & Zhang, 2008; O’Connor et al, 2016), Longipterygidae (Chiappe et al, 2007; O’Connor et al, 2009), and Bohaiornithidae (Hu et al, 2011; Wang et al, 2014), the monophyly of which needs to be further tested. Recent studies on these birds have begun to explore their aerodynamic properties 2014) suggesting that early in their evolutionary history, enantiornithines developed various styles of intermittent flight (e.g., bounding, flap-gliding)

Methods

Results

Conclusion