Chongxi Yuan

A Nearly Modern Amphibious Bird from the Early Cretaceous of Northwestern China

Three-dimensional specimens of the volant fossil bird Gansus yumenensis from the Early Cretaceous Xiagou Formation of northwestern China demonstrate that this taxon possesses advanced anatomical features previously known only in Late Cretaceous and Cenozoic ornithuran birds. Phylogenetic analysis recovers Gansus within the Ornithurae, making it the oldest known member of the clade. The Xiagou Formation preserves the oldest known ornithuromorph-dominated avian assemblage. The anatomy of Gansus, like that of other non-neornithean (nonmodern) ornithuran birds, indicates specialization for an amphibious life-style, supporting the hypothesis that modern birds originated in aquatic or littoral niches.

An Early Ostrich Dinosaur and Implications for Ornithomimosaur Phylogeny

Abstract A new ornithomimosaur from the Yixian Formation of Liaoning Province Peoples Republic of China is described. These beds are near the Jurassic-Cretaceous boundary. This specimen is interesting because it has several primitive characters for ornithomimosaurs such as teeth and a short first metacarpal. This taxon is placed in a phylogenetic analysis of Coelurosauria and shown to be near the base of the ornithomimosaur clade. Using this phylogeny we comment on the biogeographic history of this group.

Palaeontology: 'modern' feathers on a non-avian dinosaur.

Discoveries of integumentary coverings on non-avian theropod dinosaurs are becoming commonplace. But the only definitive evidence so far that any of these animals had feathers as we know them today has come from the oviraptorosaur Caudipteryx and the enigmatic coleurosaur Protarchaeopteryx, both of which are considered by some to be secondarily flightless birds. Here we describe the occurrence of pinnate feathers, which clearly feature a rachis and barbs, on a small, non-avian dromaeosaur from northern China. This finding indicates that feathers of modern aspect evolved in dinosaurs before the emergence of birds and flight.

Palaeontology: pterosaur egg with a leathery shell.

The recent discovery of a pterosaur egg with embryonic skeleton and soft tissues from the Yixian Formation confirmed that the flying pterosaurs were oviparous. Here we describe another pterosaur egg whose exquisite preservation indicates that the shell structure was soft and leathery.