Early Cretaceous birds

Confuciusornithidae is an extinct family of pygostylian avialans known from the Early Cretaceous, found in northern China. They are commonly placed as a sister group to Ornithothoraces, a group that contains all extant birds along with their closest extinct relatives. Confuciusornithidae contains four genera, possessing both shafted and non-shafted (downy) feathers. Some specimens probably referable to this clade represents one of the earliest known fossil evidence of primary feather moulting. They are also noted for their distinctive pair of ribbon-like tail feathers of disputed function.

Hongshanornithidae is an extinct group of early ornithuromorph birds from the early Cretaceous period of China. It includes the genera Hongshanornis (the type genus) and Tianyuornis from the Yixian Formation of Inner Mongolia, Longicrusavis from the Yixian Formation of Liaoning Province, Parahongshanornis from the Jiufotang Formation of Liaoning Province, and Archaeornithura, the oldest known member, from the Huajiying Formation of Hebei Province.

Pengornithidae is a group of early enantiornithines from the early Cretaceous Period of China, with the putative member Falcatakely possibly extending this clade's range into the Late Cretaceous of Madagascar, and several putative pengornithids also hail from this formation. Specimens of these animals have been found both in the Huajiying Formation and Jiufotang Formation of Liaoning and Hebei provinces, dating from the Hauterivian age (130.7 million years ago) to the Aptian age (120 million years ago).

Omnivoropterygidae (meaning "omnivorous wings") is a family of primitive avialan dinosaurs known exclusively from the Jiufotang Formation of China, though putative omnivoropterygids are known from the Maevarano Formation of the Maastrichtian of Madagascar. They had short skeletal tails and unusual skulls with teeth in the upper, but not lower, jaws. Their unique dentition has led some scientists to suggest an omnivorous diet for them. The family was named by Stephen A. Czerkas & Qiang Ji in 2002, though its junior synonym Sapeornithidae is often used instead, though it was named four years lat

Songlingornithidae is a family of basal euornithean dinosaurs from the Early Cretaceous of China. All known specimens come from the Jiufotang Formation and the Yixian Formation, dating to the early Barremian and Aptian ages, 125–120 million years ago.

Jinguofortisidae is an extinct family of early pygostylian dinosaurs known from the Early Cretaceous. They were found in northern China.

Ilerdopteryx is an extinct genus of birds, perhaps an enantiornithine, from the Lower Cretaceous La Pedrera de Rúbies Formation lithographic limestone of Spain. The type species, I. viai, is known only from a collection of isolated contour feathers.

Monoenantiornis is an extinct genus of enantiornithean that inhabited China during the Cretaceous period. It is a monotypic genus known from the species M. sihedangia.