Baicaigou, Toutai: Late/Upper Barremian - Early/Lower Aptian, China
collected 1999-2004

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Actinopteri
Longdeichthys sp. Liu 1982
Yuan 2008
Jinanichthys sp. Ma and Sun 1988
Yuan 2008
Reptilia
Hyphalosaurus sp. Gao et al. 1999
    = Hyphalosaurus baitaigouensis Ji et al. 2004
Yuan 2008
Hyphalosaurus baitaigouensis n. sp. Ji et al. 2004
Gao and Ksepka 2008 5 individuals
CAGS-IG-03-7-02 (holotype partial skeleton), PKUP V1056-1058, BMNHC V014- 053, LPMC R-00052, LPMC R-00065-00066, and many unnumbered specimens in BMNHC, IVPP, LPMC and PKUP collections; Additional remains discussed by Hou et al. (2010) comprise LPM-R169 (egg, containing an embryo) and LPM-R168 (egg associated with a partially hatched neonate); Ji et al. (2010) suggested the presence of viviparity in an additional specimen (CAGS-IG-06131)
Monjurosuchus splendens Endo 1940
Gao and Li 2007 1 individual
BMNHC V073
Reptilia - Dromaeosauridae
Sinornithosaurus haoiana n. sp. Liu et al. 2004
Liu et al. 2004 1 specimen
synonym of Sinornithosaurus millenii
D2140 (3 measurements)
Reptilia - Troodontidae
Jianianhualong tengi n. gen., n. sp. Xu et al. 2017
Xu et al. 2017 1 specimen
DLXH 1218
Reptilia
Jixiangornis orientalis Ji et al. 2002
Yuan 2008
Shenzhouraptor sinensis n. gen., n. sp. Ji et al. 2002
Ji et al. 2002 1 individual
LPM 193
Enantiornithes indet. Walker 1981
Didactylornis jii n. gen., n. sp. Yuan 2008
Yuan 2008 1 individual
synonym of Sapeornis chaoyangensis
CDPC-02-08-001
Reptilia - Iguanodontidae
Jinzhousaurus yangi n. gen., n. sp. Wang and Xu 2001
1 individual
IVPP V12691 (9 measurements)
Reptilia
Pterodactyloidea indet. Plieninger 1901
Istiodactylus sinensis n. sp. Andres and Ji 2006
Andres and Ji 2006 1 individual
NGMC 99-07-011, relatively complete skeleton
Sinamiidae
Sinamia sp.
Yuan 2008
see common names

Geography
Country:China State/province:Liaoning County:Yixian
Coordinates: 41.1° North, 121.1° East (view map)
Paleocoordinates:43.9° North, 123.1° East
Basis of coordinate:based on nearby landmark
Geographic resolution:small collection
Time
Period:Cretaceous Epoch:Early/Lower Cretaceous
Stage:Barremian
Key time interval:Late/Upper Barremian - Early/Lower Aptian
Age range of interval:125.77000 - 119.50000 m.y. ago
Age estimate:maximum 122.1 ± 0.3 Ma (Ar/Ar)
Stratigraphy
Geological group:Jehol Formation:Yixian Member:Dakangpu
Stratigraphic resolution:group of beds
Stratigraphy comments: middle part of formation, originally assigned to Yixian Fm., comparable to Dawangzhangzi Bed. "middle part" of formation.
The Yixian Formation can be subdivided into five units, in ascending order, Lujiatun unit, Lower Lava, Jianshangou unit, Upper Lava, Dawangzhangzi unit, Jingangshan unit, and Huanghuashan unit. Most of the Jehol fossils from the Yixian Formation are preserved in four beds, that is, the Lujiatun bed (recalculated age is 124.0 ± 1.0/1.3 Ma, He et al., 2006), the Jianshangou bed (125.43 ± 0.50/0.88 Ma, Swisher et al., 1999), the Dawangzhangzi bed, and Jinggangshan bed (~122 Ma, Smith et al., 1995).U-Pb dating suggests that the Huangbanjigou section ranges from 124.9 ± 1.7 Ma to 122.8 ± 1.6 Ma (Yang et al., 2007). Chang et al. (2017) obtained Ar/Ar ages of 125.8 ± 1.0 Ma and 126.0 ± 0.8 Ma from the Lujiatun Unit, the lowest part of the Yixian Formation, below the lacustrine shales.
He et al. (2004) reported a 40Ar/39Ar age of 120.3 ± 0.7 Ma for a tuff layer in the lower part of the Jiufotang Formation, and Chang et al. (2009) obtained a 40Ar/39Ar age of 122.1 ± 0.3 Ma for a tuff layer from the lowermost part of the Jiufotang Formation. Yu et al. (2021) dated an ash bed just above the Yixian/Jiufotang formation boundary to 122.0 ± 0.9 Ma and three tuff beds from the Xiaotaizi section to 118.9 ± 0.8 Ma, 118.8 ± 0.6 Ma, and 118.6 ± 1.1 Ma. These ages suggest that the Jiufotang Formation in Jianchang Basin was deposited at ca. 122.0–118.9 Ma.
Olierrok et al. (2019) used a selection of U-Pb and 40Ar-39Ar geochronology to place the Barremian–Aptian boundary (the base of the Chron M0r) between 123.8 and 121.8 Ma. The GTS 2020 uses an age of 121.4 Ma for the base of the Aptian, and multiproxy orbital tuning gives an age of 120.2 Ma for the Barremian-Aptian boundary (Leandro et al., 2022). Therefore, the Yixian Formation should be entirely Late Barremian, with the Jiufotang Formation deposited in the Early Aptian (or latest Barremian at its base).
Lithology and environment
Primary lithology:tuffaceous "shale"
Secondary lithology: mudstone
Includes fossils?Y
Lithology description: from a "tuffaceous" horizon: lithified based on matrix surrounding figured specimen (pterosaur)
Environment:lacustrine indet.
Taphonomy
Modes of preservation:body,adpression
Size of fossils:macrofossils
Preservation of anatomical detail:excellent
Articulated whole bodies:some
Associated major elements:some
Fragmentation:occasional
Spatial resolution:parautochthonous
Collection methods and comments
Collection methods:surface (in situ),mechanical,field collection,survey of museum collection
Reason for describing collection:taxonomic analysis
Museum repositories:IVPP
Collection dates:1999-2004
Collection method comments: pterosaur was "collected in 1999 by a local farmer and then directly acquired by the NGMC"
Metadata
Also known as:Jonzhou, Baitaigou, Baicai Gou
Database number:67611
Authorizer:M. Carrano, R. Benson Enterer:M. Carrano, R. Benson
Modifier:M. Carrano Research group:vertebrate
Created:2006-11-27 11:29:42 Last modified:2023-04-28 11:16:27
Access level:the public Released:2006-11-27 11:29:42
Creative Commons license:CC BY
Reference information

Primary reference:
19265.ETE X. Wang and X. Xu. 2001. A new iguanodontid (Jinzhousaurus yangi gen. et sp. nov.) from the Yixian Formaton of western Liaoning, China. Chinese Science Bulletin 46(19):1669-1672 [M. Carrano/M. Carrano]

Secondary references:

43669 R. Amiot, X. Wang, Z. Zhou, X. Wang, E. Buffetaut, C. Lécuyer, Z. Ding, F. Fluteau, T. Hibino, N. Kusuhashi, J. Mo, V. Suteethorn, Y. Wang, X. Xu, and F. Zhang. 2011. Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates. Proceedings of the National Academy of Sciences 108(13):5179-5183 [M. Carrano/M. Carrano]
28404 B. Andres and Q. Ji. 2006. A new species of Istiodactylus (Pterosauria, Pterodactyloidea) from the Lower Cretaceous of Liaoning, China. Journal of Vertebrate Paleontology 26(1):70-78 [J. Alroy/J. Alroy]
50540 K. Carpenter and Y. Ishida. 2010. Early and "middle" Cretaceous iguanodonts in time and space. Journal of Iberian Geology 36(2):145-164 [M. Carrano/M. Carrano]
37788 K. -Q. Gao and D. T. Ksepka. 2008. Osteology and taxonomic revision of Hyphalosaurus (Diapsida: Choristodera) from the Lower Cretaceous of Liaoning, China. Journal of Anatomy 212:747-768 [R. Benson/R. Benson]
24703ETE K.-Q. Gao and Q. Li. 2007. Osteology of Monjurosuchus splendens (Diapsida: Choristodera) based on a new specimen from the Lower Cretaceous of western Liaoning, China. Cretaceous Research 28:261-271 [M. Carrano/M. Carrano]
44163 L.-H. Hou, P.-P. Li, D. T. Ksepka, K.-Q. Gao, and M. A. Norell. 2010. Implications of flexible-shelled eggs in a Cretaceous choristoderan reptile. Proceedings of the Royal Society, Series B 277:1235-1239 [P. Mannion/P. Mannion]
30691ETE Q. Ji, S. Ji, H. You, J. Zhang, C. Yuan, X. Ji, J. Li and Y. Li. 2002. [Discovery of an Avialae bird from China, Shenzhouraptor sinensis gen. et sp. nov]. Geological Bulletin of China 21(7):363-369 [M. Carrano/M. Carrano]
44164 Q. Ji, X.-C. Wu, and Y.-N. Cheng. 2010. Cretaceous choristoderan reptiles gave birth to live young. Naturwissenschaften 97:423-428 [P. Mannion/P. Mannion]
30569ETE J. Liu, S. Ji, F. Tang and C. Gao. 2004. A new species of dromaeosaurids from the Yixian Formation of western Liaoning. Geological Bulletin of China 23(8):778-783 [M. Carrano/M. Carrano]
67478 X. Xu, P. Currie, M. Pittman, L. Xing, and Q. Meng, J., D. Hu and C. Yu. 2017. Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features. Nature Communications 8:14972:1-12 [G. Lloyd/G. Lloyd/M. Carrano]
30690ETE C. Yuan. 2008. A new genus and species of Sapeornithidae from Lower Cretaceous in western Liaoning, China. Acta Geologica Sinica 82(1):48-55 [M. Carrano/M. Carrano]
62117 Z. H. Zhou. 2006. Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives. Geological Journal 41:377-393 [M. Uhen/F. Villegas-Garin/M. Clapham]