“Xiagou Formation”的意思、由来-开放百科全书

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Xiagou Formation

释义

Fossil content
See also
References
Bibliography
Further reading

{{Infobox rockunit
| name = Xiagou Formation
| image =
| caption =
| type = Geological formation
| period = Aptian
| age = Aptian
~{{fossil range|125|113}}
| prilithology = Mudstone
| otherlithology = Shale, siltstone
| namedfor = Xiagou
| namedby =
| region = Gansu
| country = {{CHN}}
| coordinates = {{coord|39.9|N|96.8|E|display=inline,title}}
| paleocoordinates = {{coord|39.1|N|97.5|E|display=inline}}
| unitof = Xinminpu Group
| subunits =
| underlies = Zhonggou Formation
| overlies = Chijinpu Formation
| thickness =
| extent = Changma Basin
| area =
| map = {{Location map+ | China
| relief = 1
| width = 250
| float = center
| places =
| lat_deg = 39.9
| lon_deg = 96.8
| mark = Green pog.svg
| marksize = 12
}}
| map_caption =
}}

The Xiagou Formation is the middle strata of the Xinminpu Group. It is named for its type site in Xiagou, in the Changma Basin of Gansu Province, northwestern China and is considered Early Cretaceous in age. It is known outside the specialized world of Chinese geology as the site of a Lagerstätte in which the fossils were preserved of Gansus yumenensis, the earliest true modern bird. The laminated yellowish mudstones of the Xiagou Formation are the lithified remnants of varves that were laid down as extremely fine silt settled to the bottom of a tranquil freshwater lake. The result was dense anoxic bottom sediment, where the lack of bacteria slowed the processes of decay, preserving uncompressed fossils in details that include feather impressions and remnants of the webbing between the bird's toes.

The age of the formation has not yet been confidently determined. The underlying Chijinpu Formation is likely the same age as the Jehol Group due to the presence of similar fossils, meaning that the Xiagou Formation is probably slightly younger than the Jehol biota, dating to around the middle Aptian.^[1]

Fossil content

The Xiagou Formation is particularly noted for its high diversity of ancient birds. These include both modern birds close to the ancestors of living species, and related lineages now entirely extinct:^[2]

: //Enantiornithes">Enantiornithes

Avimaia schweitzerae {{small|Bailleul et al. 2019}}
Dunhuangia cuii {{small|Wang et al. 2015}}
Feitianius paradisi {{small|O'Connor et al. 2015}}
Qiliania graffini {{small|Ji et al. 2011}}

: //Ornithuromorph">Ornithuromorphs

Changmaornis houi {{small|Wang et al. 2013}}
Gansus yumenensis {{small|Hou & Liu 1984^[3]}}
Jiuquanornis niui {{small|Wang et al., 2013}}
Yumenornis huangi {{small|Wang et al., 2013^[4]}}

Reptiles

Changmachelys bohlini {{small|Brinkman et al. 2013^[5]}}
Testudines indet.

Insects

Blattapterix gansu {{small|Vršanský 2003}}
Cretacechorista qilianshanensis {{small|Hong et al. 1989}}
Eurycoleus arcuatus, E. clypeolatus, E. dimorphocellatus, E. parvus {{small|Hong 1982}}
Glottocoleus lenticulata, G. stellatus {{small|Hong 1982}}
Mesoblattina cretacea {{small|Hong 1982}}
Mesocoleus zhonggouense {{small|Hong 1982}}
Mesotricupes reticulatus {{small|Hong 1982}}
Petalocupes arcus {{small|Hong 1982}}
Phyllocoleus striolatus {{small|Hong 1982}}
Planocoleus ensatus {{small|Hong 1982}}
Pleurocoleus catenatus {{small|Hong 1982}}
Spinus yumenense {{small|Hong 1982}}
Tetillopsis parvula {{small|Hong 1982}}
Yumenocoleus intermedius, Y. lineatus, Y. longus {{small|Hong 1982}}

Fish

Shuleichthys brachypteryx {{small|Murray et al. 2010}}

Other fossils from the Xiagou Formation are characteristic of an Early Cretaceous lake ecology. There are fossils of abundant fish fauna, Charophyta and ostracods.

References

1. ^You et al., 2006
2. ^Changma, Yumen at Fossilworks.org
3. ^Weishampel et al., 2004, pp. 553-556
4. ^Wang et al., 2013, p.2
5. ^Brinkman et al., 2013, p.369

Bibliography

{{cite LSA |last=Brinkman |first=D.B. |last2=Yuan |first2=C.-X. |last3=Ji |first3=Q. |last4=Ji |first4=D. |last5=You |first5=H. |year=2013 |title=A new turtle from the Xiagou Formation (Early Cretaceous) of Changma Basin, Gansu Province, P. R. China |url=https://www.researchgate.net/publication/271742886_A_new_turtle_from_the_Xiagou_Formation_Early_Cretaceous_of_Changma_Basin_Gansu_Province_P_R_China |journal=Palaeobiodiversity and Palaeoenvironments |volume=93 |pages=367–382 |accessdate=2019-03-23}}
{{cite LSA |last=Wang |first=Y.-M. |last2=O'Connor |first2=J. |last3=Li |first3=D.-Q. |last4=You |first4=H.-L. |year=2013 |title=Previously unrecognised ornithuromorph bird diversity in the Early Cretaceous Changma Basin, Gansu Province, northwestern China |url=https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0077693&type=printable |journal=PLoS ONE |volume=8 |pages=1–14 |accessdate=2019-03-23}}
{{cite LSA |last=Weishampel |first=David B. |last2=Dodson |first2=Peter |last3=Osmólska |first3=Halszka (eds.) |year=2004 |title=The Dinosauria, 2nd edition |url=https://books.google.com.co/books/about/The_Dinosauria.html?id=vtZFDb_iw40C&redir_esc=y |publisher=Berkeley: University of California Press |pages=1–880 |accessdate=2019-02-21}}{{ISBN|0-520-24209-2}}
{{cite LSA |last=You |first=Hai-lu |last2=Lamanna |first2=Matthew C. |last3=Harris |first3=Jerald D. |last4=Chiappe |first4=Luis M. |last5=O'Connor |first5=Jingmai |last6=Ji |first6=Shu-an |last7=Lü |first7=Jun-chang |last8=Yuan |first8=Chong-xi |last9=Li; Zhang, Xing; Lacovara, Kenneth J.; Dodson, Peter and Ji, Qiang |first9=Da-qing |year=2006 |title=A Nearly Modern Amphibious Bird from the Early Cretaceous of Northwestern China |url=https://www.researchgate.net/publication/7005790_A_Nearly_Modern_Amphibious_Bird_from_the_Early_Cretaceous_of_Northwestern_China |journal=Science |volume=312 |issue= |pages=1640–1643 |accessdate=2019-03-23}}

Fossil content

See also

References

Bibliography

Further reading