Huajiying Formation

Stratigraphic range: Valanginian-Aptian
Type| Geological formation
Unit of| Jehol Group
Sub-units| Guohedao Member,
Nianzigou Member,
Qiaotou Member,
Sichakou Member
Underlies| Quingshila Formation
Overlies| Dabeigou Formation
Location
Region| Hebei
Country|  China

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

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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

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

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Color key
| Taxon | Reclassified taxon | Taxon falsely reported as present | Dubious taxon or junior synonym | Ichnotaxon | Ootaxon | Morphotaxon

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| Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.

### Theropods

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Genus  | Species  | County  | Member  | Abundance  | Notes  | Images

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Archaeornithura | A. meemannae | Fengning | Sichakou Member  |  | An ornithuromorph | Archaeornithura
Cruralispennia | C. multidonta |  | Sichakou Member  |  | An enantiornithine | Cruralispennia
Eopengornis | E. martini |  |  |  | An enantiornithine  |

"Hebeiornis"

"H. fengningensis"

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Qiaotou Member

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Nomen nudum/objective junior synonym of Vescornis

Jibeinia

J. luanhera

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Qiaotou Member

|  | An enantiornithine

Jinfengopteryx

J. elegans

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Qiaotou Member

|  | A troodontid |  Jinfengopteryx

Protopteryx

P. fengningensis

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Sichakou Member

|  | An enantiornithine

Shenqiornis[1]

S. mengi

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Qiaotou Member

|  | An enantiornithine

Vescornis

V. hebeiensis

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Qiaotou Member

|  | An enantiornithine
Xunmenglong | X. yinlianglis |  |  |  | A compsognathid

### Pterosaurs

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Genus | Species | County  | Member | Abundance | Notes | Images

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Cratonopterus[5] | C. huabei | Fengning |  |  | A ctenochasmatid |
Ornithocheiroidea[6] | Indeterminate  | Fengning  |  |  | Partial skeleton of an indeterminate ornithocheiroid  |

### Fishes

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Genus  | Species  | County  | Member  | Abundance  | Notes  | Images

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Lycoptera

L. davidi

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Also present in the Jiufotang Formation & Yixian Formation

An osteoglossomorph

|  Lycoptera davidi Yanosteus longidorsalis

L. tokunagai

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Peipiaosteus

P. fengningensis

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A fish related to sturgeons

Protopsephurus

P. liui

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Also present in the Jiufotang & Yixian Formations

A paddlefish

Yanosteus

Y. longidorsalis

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Also present in the Yixian Formation

A peipiaosteid

### Invertebrates

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Genus | Species | County  | Member | Abundance | Notes | Images

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Yanjiestheria | Y. huajiyingensis |  |  | Well-preserved remains and eggs.[7] | A spinicaudatan |

## References

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1. ^ a b 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). E22370. Bibcode:2023Heliy...922370J. doi:10.1016/j.heliyon.2023.e22370. PMC 10709016. PMID 38076164.
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. 35 (7): 1129–1135. doi:10.1080/08912963.2022.2079085. ISSN 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: 105425. doi:10.1016/j.cretres.2022.105425. ISSN 0195-6671. S2CID 253998860.