The Huajiying Formation is a geological formation in Hebei

Hebei

' is a province of the People's Republic of China in the North China region. Its one-character abbreviation is "" , named after Ji Province, a Han Dynasty province that included what is now southern Hebei...

, People's Republic of China

People's Republic of China

China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

. Known for its fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s including primitive bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, the age of the ormation is uncertain. It may represent an early portion of the Jehol Biota

Jehol Biota

The Jehol Biota includes all the living organisms - the ecosystem - of northeastern China between 133 to 120 million years ago. This is the Lower Cretaceous ecosystem which left fossils in the Yixian Formation and Jiufotang Formation. It is also believed to have left fossils in the Sinuiju series...

, dating to somewhere in the early Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 or late Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 periods. It may correlate with the early Cretaceous Dadianzi Formation and parts of the Yixian Formation

Yixian Formation

The Yixian Formation is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans 11 million years during the early Cretaceous period...

, with an age range between 140 and 122 Ma ago. It contains the Qiaotou Member, sometimes treated as a distinct formation.

Age and stratigraphy

The Huajiying Formation contains the following members, in order from youngest to oldest:

• 5th Volcanic Member
• Guohedao Sedimentary Member
• 4th Volcanic Member
• Nianzigou Sedimentary Member
• 3rd Volcanic Member
• Qiaotou Sedimentary Member
• 2nd Volcanic Member
• Sichakou Sedimentary Member
• 1st Volcanic Member

The age of the formation is uncertain. Ji and colleagues suggested in 2008 that the Qiaotou Member correlates with the Dawangzhangzi bed of the Yixian Formation

Yixian Formation

The Yixian Formation is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans 11 million years during the early Cretaceous period...

, dated to ~122 Ma ago by Zhou in 2006. Ji et al. also suggested that the lower Sichakou Member correlates with the Dadianzi Formation, dated to 140 Ma ago by Tian and colleagues in 2003.

Paleobiota

The faunal lists below are based on a survey of the Huajiying Formation by Jin Fan and colleagues in 2008, unless otherwise noted.

Birds and other theropods

Genus	Species	County	Member	Abundance	Notes	Images
"Hebeiornis"	"H. fengningensis"		Qiaotou Member		Nomen nudum/objective junior synonym of Vescornis
Jibeinia Jibeinia Jibeinia is a Genus of enantiornithine bird. Only one species is known, Jibeinia luanhera. It is known from one holotype fossil found in the Liaoning province, People's Republic of China. This fossil is now lost...	J. luanhera		Qiaotou Member		An enantiornithine Enantiornithes Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
Jinfengopteryx Jinfengopteryx Jinfengopteryx is a genus of maniraptoran dinosaur. It was found in the Qiaotou member of the Huajiying Formation of Hebei Province, China, and is therefore of uncertain age...	J. elegans		Qiaotou Member		A troodontid Troodontidae Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and scrappy and they have therefore been allied, at various times, with many dinosaurian lineages...
Protopteryx Protopteryx Protopteryx is an extinct genus of bird, perhaps an enantiornithine, from the Cretaceous in China. The type species is P. fengningensis...	P. fengningensis		Sichakou Member		An enantiornithine
Shenqiornis Shenqiornis Shenqiornis is a genus of enantiornithine . It was found in the Qiaotou member of the Huajiying Formation of Hebei Province, China, and is therefore of uncertain age. The Qiaotou Member may correlate with the more well-known Early Cretaceous Yixian Formation, and so probably dates to around 122 Ma...	S. mengi		Qiaotou Member		An enantiornithine
Vescornis Vescornis Vescornis is a genus of enantiornithine bird. One species is named, V. hebeiensis. The holotype fossil is in the collection of the Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences. Its catalog number is CAGS 130722. The fossil was found in Early Cretaceous rocks first...	V. hebeiensis		Qiaotou Member		An enantiornithine

Fishes

Genus	Species	County	Member	Abundance	Notes	Images
Lycoptera Lycoptera Lycoptera is a genus of fish that lived from the late Jurassic to Cretaceous periods in present-day China, Korea, Mongolia and Siberia. It is known from abundant fossils representing sixteen species, and is an important index fossil used to date geologic formations in China...	L. davidi			Also present in the Jiufotang Formation Jiufotang Formation The Jiufotang Formation is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms. . It is a member of the Jehol group. The exact age of the Jiufotang has been debated for years, with...  & Yixian Formation Yixian Formation The Yixian Formation is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans 11 million years during the early Cretaceous period...	An osteoglossiform Osteoglossiformes Osteoglossiformes is a relatively primitive order of ray-finned fish that contains two sub-orders, the Osteoglossoidei and the Notopteroidei. All of the living species inhabit freshwater...
	L. tokunagai
Peipiaosteus Peipiaosteus Peipiaosteus is an extinct genus of prehistoric bony fish. This is a very rare species of sturgeon from Jiufotang Formation, Pani Lake, Liaoning Province, China. -See also:* Prehistoric fish* List of prehistoric bony fish...	P. fengningensis				A fish related to sturgeon Sturgeon Sturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genera Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. The term includes over 20 species commonly referred to as sturgeon and several closely related species that have distinct common... s
Protopsephurus	P. liui			Also present in the Jiufotang & Yixian Formations	A paddlefish Paddlefish Paddlefish are primitive Chondrostean ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated, spatula-like snout, called a rostrum, which is longer than the rest of the head...
Yanosteus	Y. longidorsalis			Also present in the Yixian Formation	A peipiaosteid