An international team of paleontologists has described a new ornithuromorph bird that lived during the Hauterivian stage of the Early Cretaceous epoch, approximately 131 million years ago.
Archaeornithura meemannae stood about 6 inches (15 cm) tall on two legs that had no feathers. Image credit: Zongda Zhang / Institute of Vertebrate Paleontology and Paleoanthropology, Bejing.
The new bird belongs to Ornithuromorpha, a clade of birds that contains all extinct and extant species but not the Mesozoic Enantiornithes.
Until now the earliest record of this group was from the lower Cretaceous Yixian Formation (125 million years ago), the middle phase in the evolution of the Jehol Biota – the most important and diverse fossil avifauna known to paleontologists.
The bird, named Archaeornithura meemannae, represents a new genus and species, and its discovery was reported May 5 in the journal Nature.
The genus name, Archaeornithura, is derived from Greek ‘Archae’ and ‘ornithura’, meaning ‘ancient ornithuromorph.’ The species name honors paleontologist Dr Meemann Chang, for her continuous support of the study of the Jehol Biota.
Two partial skeletons of Archaeornithura meemannae were recovered from the Huajiying Formation in Sichakou basin, Fengning County, Hebei, northeastern China.
“The specimens preserve fairly advanced plumage including a well-developed alula (bastard wing) and fan-shaped rectrices. Both the alula and a fan-shaped tail are aerodynamically important for living birds during slow flight and increases manoeuvrability,” the paleontologists wrote in the paper.
“Bird fossils are extremely rare in the Mesozoic fossil record, and until the wealth of specimens discovered from Early Cretaceous deposits in northeastern China, very little was known about the early evolution of birds.”
“The Jehol Biota encapsulates a unique window into the biology and morphology of the oldest known avifauna.”
Holotype of Archaeornithura meemannae. Anatomical abbreviations: ba – basicranium; co – coracoid; cv – cervical vertebrae; fe – femur; fi – fibula; fu – furcula; hu – humerus; ra – radius; re – rectrices; ti – tibiotarsus; tm – tarsometatarsus; ul – ulna. Scale bar – 10 mm. Image credit: Min Wang et al.
“Until now no ornithuromorphs had been described from the Huajiying Formation, which preserves very few fossil birds; because diversity is low and geographic area is restricted, the Huajiying Formation is interpreted as the earliest stage in the diversification of the Jehol Biota.”
“However, the discovery of a new species belonging to the specialized clade of waders – the Hongshanornithidae, indicates that ornithuromorphs themselves were already quite specialized at this point in their evolution.”
“This also strongly supports inferences that this clade originated in a semi-aquatic environment.”
The two specimens of Archaeornithura meemannae are housed in the Tianyu Natural History Museum of Shandong and are publicly accessible.
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Min Wang et al. 2015. The oldest record of ornithuromorpha from the early cretaceous of China. Nature Communications 6, article number: 6987; doi: 10.1038/ncomms7987
