Yuornis junchangi gen. et sp. nov. (1 Viewer)

[Fred Ruhe]

Li Xu, Eric Buffetaut, Jingmai O'Connor, Xingliao Zhang, Songhai Jiam Jiming Zhang, Huali Chang & Haiyan Tong, 2021

A new, remarkably preserved, enantiornithine bird from the Upper Cretaceous Qiupa Formation of Henan (central China) and convergent evolution between enantiornithines and modern birds

Geological Magazine. in press.
doi:10.1017/S0016756821000807

Abstract: A new, remarkably preserved, enantiornithine bird from the Upper Cretaceous Qiupa Formation of Henan (central China) and convergent evolution between enantiornithines and modern birds | Geological Magazine | Cambridge Core

A new enantiornithine bird is described on the basis of a well preserved partial skeleton from the Upper Cretaceous Qiupa Formation of Henan Province (central China). It provides new evidence about the osteology of Late Cretaceous enantiornithines, which are mainly known from isolated bones; in contrast, Early Cretaceous forms are often represented by complete skeletons. While the postcranial skeleton shows the usual distinctive characters of enantiornithines, the skull displays several features, including confluence of the antorbital fenestra and the orbit and loss of the postorbital, evolved convergently with modern birds. Although some enantiornithines retained primitive cranial morphologies into the latest Cretaceous Period, at least one lineage evolved cranial modifications that parallel those in modern birds.

The paper describes Yuornis junchangi gen. et sp. nov.
Enjoy,

Fred

 

[Fred Ruhe]

Systematic palaeontology

Aves Linnaeus 1758
Ornithothoraces Chiappe 1995
Enantiornithes Walker 1981
Yuornis junchangi gen. et sp. nov.

Holotype. Henan Museum of Natural History, L-08-7-3, an
articulated partial skeleton with complete skull (Fig. 1).

Etymology. ‘Yu’ refers to an ancient name for Henan, the province where the specimen was found. Species name in honour of our late colleague Professor Lü Junchang (Chinese Academy of Geological Sciences), who was involved in the study but passed away on 9 October 2018.

Locality and horizon. Near Qiupa village, Luanchuan county, western Henan Province (north-central China). Continental red beds of the Qiupa Formation, Upper Cretaceous (Bureau of Geology and Mineral Resources of Henan Province, 1989; Zhou, 2005). The specimen was found in the course of excavations carried out by the Henan Museum of Natural History at a locality which yielded a diverse Late Cretaceous vertebrate assemblage (Xu et al. 2011) including lizards, turtles, mammals and dinosaurs.

Diagnosis. An edentulous enantiornithine (large scapular acromion; proximal margin of humerus saddle-shaped with concave cranial and convex caudal surfaces; minor metacarpal projecting distally further than major metacarpal; and femur with well developed posterior trochanter) with the following diagnostic features: both the antorbital fenestra and supratemporal fenestra completely confluent with orbit; quadratojugal with hook-like process that curves around the lateral condyle of the quadrate; acromion process with narrow pedicel with a sulcus on the lateral surface; deltopectoral crest more than one-third the length of the humerus and separated from the dorsal tubercle (continuous in most enantiornithines). Differs from Gobipteryx in having a proportionately longer and narrower rostrum that is not upturned rostrally, presence of a well developed nasal process on the maxilla (absent in Gobipteryx) and external nares that are proportionately narrower (ventral and caudal margins forming a 143° angle in Yuornis versus 118° in Gobipteryx) (see online Supplementary Materials, available at Geological Magazine | Cambridge Core, for differential diagnosis).

Fred


Fig. 1. Type specimen of Yuornis junchangi, L08-7-3, from the Upper Cretaceous Qiupa Formation of Henan, China. lf – left femur; lh – left humerus; li – left ilium; lm – left metacarpals; ls – left scapula; lu – left ulna; m – mandible; r – ribs; rc – right coracoid; rh – right humerus; rm – right metacarpals; rr – right radius; ru – right ulna; s – skull;
sy – synsacrum; up – ungual phalanx.
Scale bar: 50 mm.

Fig. 2. Cladogram showing the position of Yuornis. See online Supplementary Material for phylogenetic methods and full results, available at Geological Magazine | Cambridge Core.