Dengying Formation

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Dengying Formation
Stratigraphic range: Ediacaran
~551–541 Ma
File:DuoshantuoDengyingTransition.jpg
Transition between uppermost Doushantuo Formation and lowermost Dengying Formation
TypeFormation
Sub-unitsSee: Members
UnderliesYanjiahe Formation[1]
OverliesDoushantuo Formation
Lithology
PrimaryDolomite
OtherChert, Limestone
Location
RegionYangtze Gorges
CountryChina

The Dengying Formation is an upper Ediacaran (551-541 Ma[2]) fossiliferous geologic formation found in South China. It was deposited on a shallow marine carbonate platform.[3] It also contains a rare example of Burgess Shale-type Preservation within the Ediacaran, in the form of the Tongshan Lagerstätte.[4]

Members

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Listed by ascending age:

  • The Hamajing Member is characterized by light grey, medium- to thick-bedded dolomite, intercalated with thin layers of chert.[3]
  • The Shibantan Member is interpreted to represent a subtidal environment and is composed of dark grey, thin-bedded bituminous limestone. It is the most fossiliferous of the Dengying Formation members and has yielded several trace fossils, such as Lamonte,[5] as well as possible lobopodian trackways.[6]
  • The Baimatuo Member consists of light grey, thick-bedded dolomite.[3]

Traditionally, the Tianzhushan Member was considered to be the uppermost unit of the Dengying Formation. However, its small shelly fossils and Micrhystridium-like acritarchs are a shared characteristic with the Cambrian Yanjiahe Formation.[3] The Kuanchuanpu Formation also is occasionally placed as a member of the Dengying Formation,[7] however it is likely separate for the same reasons.

Paleobiota

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The Dengying formation is unique from other Ediacaran formations in that its top is almost right up against the Ediacaran - Cambrian boundary, with more recent organisms being described that have striking similarities with Cambrian fauna, like Alienum. There are also a lot of ichnogenera in the form of burrows, something that is common in younger Ediacaran rocks the closer to the Cambrian boundary they are.

A recent paper has also found a rare example of Burgess Shale-type Preservation outside of the known range of all members, in what is known as the Tongshan Lagerstätte. This preserves a wide range of fossil forms, including the first rangeomorph fronds with Burgess Shale-type preservation.[4]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Proarticulata

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Genus Species Notes Images
Dickinsonia[8]
  • Dickinsonia sp.
Oval to elongated motile organism. Only one incomplete specimen is known.
File:Dickinsonia costata.jpg

Petalonamae

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Genus Species Notes Images
Charniodiscus[9]
  • Charniodiscus sp.
Frondose organism.
File:Charniodiscus.png
Paracharnia[10]
  • P. denyingensis
Frondose organism.
Pteridinium[9]
  • Pteridinium sp.
Frondose organism.
File:Pteridinium simplex Namibia.JPG
Rangea[9]
  • Rangea sp.
Frondose organism.

Trilobozoa

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Genus Species Notes Images
Lobodiscus[11]
  • L. tribrachialis
Tri-radial organism.

Porifera

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Genus Species Notes Images
Helicolocellus[12]
  • H. cantori
Conical sponge, possible relations to hexactinelliid sponges.

incertae sedis

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Genus Species Notes Images
Alienum[13]
  • A. velamenus
Vetulicolian-like organism.
File:3D Reconstruction of Alienum velamenus.png
Cloudina[14]
  • Cloudina sp.
Tubular organism.
File:Cloudina NT.jpg
Curviacus[15]
  • C. ediacaranus
Elongated organism.
Conotubus[16]
  • C. hemiannulatus
Tubular organism.
Cycliomedusa[17]
  • C. jiangchuanensis
Discoid organism.
File:Cycliomedusa Reconstruction.png
Eoandromeda[4]
  • E. octobrachiata
Discoid organism.
File:Eoandromeda.jpeg
Gaojiashania[18]
  • G. cyclus
Tubular organism.
Hiemalora[9]
  • Hiemalora sp.
Discoid organism, possibly holdfasts of petalonamids.
File:Hiemalora stellaris.jpg
Palaeorhopalon[14]
  • P. spiniferum
Tubular organism.
Palaeopascichnus[4]
  • P. linearis
Palaeopascichnid organism.
Protoconites[4]
  • P. minor
Curved conical organism, possible relations to Cnidaria.
Shufangtubulus[14]
  • S. inornatus
Tubular organism.
Sinotubulites[19][14]
  • Sinotubulites sp.
  • S. baimatuoensis
  • S. hexagonus
  • S. pentacarinalis
  • S. triangularis
Tubular organism.
Wutubus[9]
  • W. annularis
Tubular organism.
Yangtziramulus[20]
  • Y. zhangi
Enigmatic organism, affinities with other forms is unknown, although possibly related to the Petalonamae, like Charnia.
Yilingia[21]
  • Y. spiciformis
Bilterian animal of unknown affinities, with possible relations to Panarthopoda or Annelida.

Flora

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Genus Species Notes Images
Longfengshania[17]
  • Longfengshania sp.
Thallus-like macroalgae.
File:Recreation of Longfengshania stipitata as algae.png
Protocodium[22]
  • P. sinense
Codiacean alga.
Baculiphyca[4]
  • B. taeniata
Thallus-like macroalgae.
Zhongbaodaophyton[4]
  • Z. robustus
Branching macroalgae.
Doushantuophyton[4]
  • D. lineare
Branching macroalgae.
Chuaria[4]
  • Chuaria sp.
Enigmatic fossil, possibly synonymous with Tawuia.
Beltanelliformis[4]
  • B. brunsae
Cyanobacterial colony.
Longifuniculum[4]
  • L. dissolutum
Whip-like macroalgae.

Microorganisms

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Genus Species Notes Images
Protolagena[23]
  • P. limbata
  • P. gaojiashanensis
  • P. papillatus
Vase-like microorganisms.
Sicylagena[23]
  • S. formosa
  • S. latistoma
Vase-like microorganisms.

Ichnogenera

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Genus Species Notes Images
Lamonte[24]
  • L. trevallis
Burrows.
Helminthoidichnites
  • Helminthoidichnites isp.
Burrows.
Shaanxilithes
  • Shaanxilithes isp.
Junior synonym of Nenoxites.
File:Shaanxilithes ningqiangensis, late Ediacaran, Shaanxi province (China).jpg
Nenoxites
  • Nenoxites isp.
Movement traces.
File:Nenoxites Curvus Drawing.jpg
Torrowangea
  • Torrowangea isp.
Burrows.

Undescribed

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Genus Species Notes Images
ESEN 0013[4]
  • ???
Tubular organism, possible affinities to Metazoa.
Undescribed rangeomorph "ESEN 0016"[4]
  • ???
Frondose organism, 3 distinct lobe-like regions, consisting of a thick stalk and two petaloids, which are made up of tightly packed branches.
Fan-shaped rangeomorphs[4]
  • ???
Two frondose organisms with a similar appearance to Bradgatia, with one of the specimens, ESEN 0018, preserving with a possible holdfast.
Undescribed rangeomorph "ESEN 0019"[4]
  • ???
Frondose organism, with a similar appearance to Charniodiscus, consisting of a thick stalk and two petaloids, which are made up of tightly packed branches, also preserves a notable holdfast.
Undescribed rangeomorph "ESEN 0020"[4]
  • ???
Elongated frondose organism, with a similar appearance to Paracharnia, consisting of a thin stalk and two petaloids, which are made up of tightly packed branches, alongside a possible holdfast at its base.
Zhenba columns[25]
  • ???
Possible affinities with coralline algae.
Baseball bat-shaped form[4]
  • ???
Baseball bat-shaped form, possibly macroalgae.
Irregular circular form[4]
  • ???
Oblong-shaped form, possibly macroalgae.
Net-like form[4]
  • ???
Netted form, possibly macroalgae.
ribbon-like form[4]
  • ???
Ribbon like form, possibly macroalgae.
Bilateria indet.
  • Unapplicable
Known to have several pairs of appendages, but its exact affinity is unknown[26]

See also

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References

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