Kaoshangtun, Shangyuan, Beipiao (DNHM): Late/Upper Barremian - Early/Lower Aptian, China
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
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Reptilia
- Troodontidae
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Mei long
Xu and Norell 2004
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1 specimen | |||||||||
| DNHM D2154, a nearly complete, articulated skeleton including skull, complete cervical series, partial dorsal series, complete sacrum and ilium, a partial pubis, complete hind limbs, fairly complete caudal series and complete forelimbs, except for the furculum and much of the left manus. The missing forelimb elements may still be present in the matrix, but are not currently exposed | ||||||||||
| see common names | ||||||||||
Geography
| Country: | China | State/province: | Liaoning | County: | Beipiao |
| Coordinates: | 41.6° North, 120.9° East (view map) | ||||
| Paleocoordinates: | 44.3° North, 122.8° East | ||||
| Basis of coordinate: | based on political unit | ||||
| Geographic resolution: | outcrop |
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 |
Stratigraphy
| Geological group: | Jehol | Formation: | Yixian | Member: | Lujiatun |
| Stratigraphic resolution: | group of beds | ||||
| Stratigraphy comments: 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: | fine,volcaniclastic,green sandy mudstone | ||
| Includes fossils? | Y | ||
| Lithology description: The specimen (DNHM D2154) is encased in green mudstone with up to fine sand-size clasts | |||
| Environment: | fluvial indet. | Tectonic setting: | volcanic basin |
| Geology comments: lowest more fluvial and volcaniclastic | |||
Taphonomy
| Modes of preservation: | body |
| Size of fossils: | macrofossils,mesofossils |
Collection methods and comments
| Collection excludes: | some macrofossils |
| Collection methods: | field collection |
| Reason for describing collection: | taxonomic analysis |
| Collection method comments: DNHM, Dalian Natural History Museum, Dalian, China | |
Metadata
| Database number: | 133789 | ||
| Authorizer: | R. Benson | Enterer: | R. Benson |
| Modifier: | M. Carrano | Research group: | vertebrate |
| Created: | 2012-09-28 23:37:51 | Last modified: | 2023-04-28 11:26:25 |
| Access level: | the public | Released: | 2012-09-28 23:37:51 |
| Creative Commons license: | CC BY |
Reference information
Primary reference:
| 43150. | C. -L. Gao, E. M. Morschauser, D. J. Varricchio, J. Liu, and B. Zhao. 2012. A second soundly sleeping dragon: new anatomical details of the Chinese troodontid Mei long with implications for phylogeny and taphonomy. PLoS ONE 7(9):e45203:1-17 [R. Benson/R. Benson/M. Carrano] |