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Chiappe L.M.,Dinosaur Institute | Bo Z.,Dalian Natural History Museum | O'Connor J.K.,Institute of Vertebrate Paleontology and Paleoanthroplogy | Chunling G.,Dalian Natural History Museum | And 6 more authors.
PeerJ | Year: 2014

The discovery of Hongshanornis longicresta, a small ornithuromorph bird with unusually long hindlimb proportions, was followed by the discovery of two closely related species, Longicrusavis houi and Parahongshanornis chaoyangensis. Together forming the Hongshanornithidae, these species reveal important information about the early diversity and morphological specialization of ornithuromorphs, the clade that contains all living birds. Here we report on a new specimen (DNHM D2945/6) referable toHongshanornis longicresta that contributes significant information to better understand the morphology, trophic ecology, and aerodynamics of this species, as well as the taxonomy of the Hongshanornithidae. Most notable are the wellpreserved wings and feathered tail of DNHM D2945/6, which afford an accurate reconstruction of aerodynamic parameters indicating that as early as 125 million years ago, basal ornithuromorphs had evolved aerodynamic surfaces comparable in size and design to those of many modern birds, and flight modes alike to those of some small living birds. © 2014 Chiappe et al. Source

Zhang Y.,Beijing Natural History Museum | O'Connor J.,Institute of Vertebrate Paleontology and Paleoanthroplogy | Di L.,Beijing Natural History Museum | Qingjin M.,Beijing Natural History Museum | And 2 more authors.
PeerJ | Year: 2014

Enantiornithines are the most diverse avian clade in the Cretaceous. However, morphological specializations indicative of specific ecological roles are not well known for this clade. Here we report on an exquisitely well-preserved specimen from the Lower Cretaceous Jehol Group of northeastern China, which pedal morphology is suggestive of a unique ecological specialization within Enantiornithes. The morphology of the new specimen is largely indistinguishable fromthat of the holotype of the bohaiornithid enantiornithine Zhouornis hani, albeit the latter is somewhat larger. The new specimen provides important and previously unknown details of the skull of Zhouornis hani, which add to the limited knowledge about the cranial anatomy and evolution of enantiornithines. The information offered by the new specimen also augments our understanding of the postcranial morphology of bohaiornithid enantiornithines, a clade that has been only recently recognized. With the description of this specimen, Zhouornis hani becomes one of the most anatomically complete known enantiornithine species, which will facilitate future morphological studies. © 2014 Zhang et al. Source

Oconnor J.K.,Dinosaur Institute | Oconnor J.K.,Institute of Vertebrate Paleontology and Paleoanthroplogy | Zhang Y.,Beijing Museum of Natural History | Chiappe L.M.,Dinosaur Institute | And 3 more authors.
Journal of Vertebrate Paleontology | Year: 2013

We report on a new enantiornithine bird, Sulcavis geeorum, gen. et sp. nov., from the Jehol Group of northeastern China. The fossil preserves robust teeth with longitudinal grooves radiating from the occlusal tip preserved in the enamel on the lingual surface. This is the first known occurrence of specialized tooth enamel within Aves. Compared with other Mesozoic groups, stomach contents are hardly ever preserved within enantiornithine specimens; therefore, this new tooth morphology reveals new evidence regarding the diversity of trophic niches occupied by the clade. © 2013 by the Society of Vertebrate Paleontology. Source

O'Connor J.K.,Institute of Vertebrate Paleontology and Paleoanthroplogy | Zhou Z.,Institute of Vertebrate Paleontology and Paleoanthroplogy
Journal of Systematic Palaeontology | Year: 2013

We review the enigmatic Chaoyangia beishanensis, one of the earliest birds described from the Jiufotang Formation, north-eastern China, and the first to be identified as an ornithurine (Aves: Ornithothoraces) and thus a member of the clade that includes living birds. A complete discussion of the validity of this taxon, which once included the holotype of Songlingornis, is provided, along with a revised diagnosis. The morphology of Chaoyangia is described, including extensive comparison with better known, recently discovered ornithurines as well as several other groups of Mesozoic birds (Confuciusornithiformes, Sapeornithiformes, Enantiornithes). Although preserved information is limited, the large number of fused sacral vertebrae and presence of a distal dorsal process on the ischium are among the features supporting early hypotheses that the only known specimen of Chaoyangia represents an ornithurine. Unique among ornithurines, Chaoyangia possesses two dorsal processes on the ischium, and thus remains a valid taxon. We include this taxon in a cladistic analysis to test morphological hypotheses regarding its systematic position. Although the results of the analysis are highly resolved and support the referral of Chaoyangia and Zhongjianornis to Ornithurae, support for the tree overall is very low. Recently discovered taxa have blurred the once clear morphological gap separating the two ornithothoracine clades (Ornithurae and Enantiornithes), and thus the increase in taxonomic diversity has caused a decrease in the stability of hypothetical relationships. © 2013 Natural History Museum. Source

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