Huajiying Formation Explained

Huajiying Formation
Type:	Geological formation
Period:	Aptian
Age:	Valanginian-Aptian
Region:	Hebei
Unitof:	Jehol Group
Subunits:	Guohedao Member, Nianzigou Member, Qiaotou Member, Sichakou Member
Underlies:	Quingshila Formation
Overlies:	Dabeigou Formation

The Huajiying Formation is a geological formation in Hebei, People's Republic of China. Known for its fossils including feathered dinosaurs, the age of the formation is uncertain. It may represent an early portion of the Jehol Biota, dating to somewhere in the early Cretaceous or late Jurassic periods. It may correlate with the early Cretaceous Dadianzi Formation and parts of the Yixian Formation, with an age range between 140 and 122 Ma ago.^[1] 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, dated to ~122 Ma ago by Zhou in 2006.^[2] 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.^[3]

Paleobiota

The faunal lists below are based on a survey of the Huajiying Formation by Jin Fan and colleagues in 2008, unless otherwise noted.^[4]

Theropods

Genus	Species	County	Member	Abundance	Notes	Images
Archaeornithura	A. meemannae	Fengning	Sichakou Member		An ornithuromorph
Cruralispennia	C. multidonta		Sichakou Member		An enantiornithine
Eopengornis	E. martini				An enantiornithine
"Hebeiornis"	"H. fengningensis"		Qiaotou Member		Nomen nudum/objective junior synonym of Vescornis
Jibeinia	J. luanhera		Qiaotou Member		An enantiornithine
Jinfengopteryx	J. elegans		Qiaotou Member		A troodontid
Protopteryx	P. fengningensis		Sichakou Member		An enantiornithine
Shenqiornis	S. mengi		Qiaotou Member		An enantiornithine
Vescornis	V. hebeiensis		Qiaotou Member		An enantiornithine
Xunmenglong	X. yinlianglis				A compsognathid

Pterosaurs

Genus	Species	County	Member	Abundance	Notes	Images
Cratonopterus^[5]	C. huabei	Fengning			A ctenochasmatid
Ornithocheiroidea^[6]	Indeterminate	Fengning			Partial skeleton of an indeterminate ornithocheiroid

Fishes

Genus	Species	County	Member	Abundance	Notes	Images
Lycoptera	L. davidi			Also present in the Jiufotang Formation & Yixian Formation	An osteoglossomorph
	L. tokunagai
Peipiaosteus	P. fengningensis				A fish related to sturgeons
Protopsephurus	P. liui			Also present in the Jiufotang & Yixian Formations	A paddlefish
Yanosteus	Y. longidorsalis			Also present in the Yixian Formation	A peipiaosteid

Invertebrates

Notes and References

1. Wang, X., O’Connor, J.K., Zhao, B., Chiappe, L.M., Gao, C. and Cheng, X. (2010). "New species of Enantiornithes (Aves: Ornithothoraces) from the Qiaotou Formation in Northern Hebei, China." Acta Geologica Sinica, 84(2): 247-256.
2. Zhou, Z. (2006). "Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives." Geological Journal, 41: 377–393.
3. Tian, S.G., Liu, Y.Q., Li, P.X., Pang, Q. and Niu, S. (2003). "Sequence stratigraphy of Jurassic-Cretaceous boundary strata in Luanping, Northern Hebei, China." Science in China Series D: Earth Sciences, 47(7): 607―617.
4. Jin, F., Zhang, F.C., Li, Z.H., Zhang, J.Y., Li, C. and Zhou, Z.H. (2008). "On the horizon of Protopteryx and the early vertebrate fossil assemblages of the Jehol Biota." Chinese Science Bulletin, 53(18): 2820-2827.
5. Jiang . Shunxing . Song . Junyi . Zhang . Xinjun . Cheng . Xin . Wang . Xiaolin . 2023-11-15 . A new pterosaur from the early stage of the Jehol biota in China, with a study on the relative thickness of bone walls . Heliyon . 9 . 12 . en . E22370 . 10.1016/j.heliyon.2023.e22370. free . 38076164 . 10709016 . 2023Heliy...922370J .
6. Zhou . Chang-Fu . Zhu . Ziheng . Chen . Jianye . 2022-05-22 . First pterosaur from the Early Cretaceous Huajiying Formation of the Jehol Biota, northern Hebei Province, China: insights on the pedal diversity of Pterodactyloidea . Historical Biology . en . 35 . 7 . 1129–1135 . 10.1080/08912963.2022.2079085 . 0891-2963.
7. Li . Gang . 2022-11-25 . New spinicaudatan species (Crustacea) of the Lower Cretaceous (Valanginian–Hauterivian) Jehol Biota from northern Hebei, China . Cretaceous Research . 143 . en . 105425 . 10.1016/j.cretres.2022.105425 . 253998860 . 0195-6671.