Earth:Yanjiahe Formation

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Yanjiahe Formation
Stratigraphic range: Ediacaran - Fortunian
~542–529 Ma
[1]
View of Yanjiahe River in Macheng, Huanggang, Hubei, the locality after which the formation is named.
TypeFormation
Sub-unitsSee: Beds
OverliesDengying Formation
Lithology
PrimaryShale, limestone, dolomite
OtherChert, phosphorite
Location
Coordinates [ ⚑ ] : 30°48′N 111°18′E / 30.8°N 111.3°E / 30.8; 111.3
Paleocoordinates [ ⚑ ] 27°36′N 160°12′E / 27.6°N 160.2°E / 27.6; 160.2
RegionHubei
CountryChina
ExtentYangtze Gorges
Type section
Named forYanjiahe River
Yanjiahe Formation is located in China
Yanjiahe Formation
Yanjiahe Formation (China)
Yanjiahe Formation is located in Hubei
Yanjiahe Formation
Yanjiahe Formation (Hubei)

The Yanjiahe Formation is an Ediacaran to Cambrian fossiliferous geologic formation found in South China.[2][3]

Dating

The Yanjiahe Formation has been dated through various methods. The top of the formation is dated at 526.5±1.1 Ma and 526.4±5.3 Ma using radiometric dating on ash beds within the area. Likewise, the base of the formation has been dated to between 542±0 Ma to 526±0 Ma through carbon isotopic correlations.[1]

Beds

The Yanjiahe Formation consists of five beds. Every bed within the formation contains fossil material.[4]

The beds are as follows, in ascending stratigraphic order (lowest to highest):

  • Bed 1 is characterized by basal dolomitic conglomerates, with banded black cherts.[4]
  • Bed 2 is mostly consists of siliceous phosphatic dolostone, with flat pebble conglomerates.[4]
  • Bed 3 is characterized by various shales, with the presence of siliceous-phosphatic nodules.[4]
  • Bed 4 is composed of carbonaceous limestones.[4]
  • Bed 5 is characterized by cherts and siliceous phosphatic dolostone, with flat pebble conglomerates.[4]

Paleobiota

The Yanjiahe Formation contains a wide range of unique organisms from the base of the Cambrian, from the probable earliest stem group echinoderm Yanjiahella, to the ecdysozoan Beretella, alongside a large wealth of early molluscs, such as Watsonella and Scenella.[3] The formation is also home to several large but incomplete ecdysozoan-like cuticles, exceeding the other fully complete ecdysozoans like Beretella and Saccorhytus in size. Despite their incompleteness, they still offer an insight into the already varied biodiversity of ecdysozoans during the early Cambrian.[5]

Cnidaria

Genus Species Notes Images
Octapyrgites[6]
  • O. elongatus
 Olivooid Medusozoan, larger than any known Olivooid.
Quadrapyrgites[7][8]
  • O. quadratacris
 Olivooid Medusozoan.
Olivooides[7][8]
  • Olivooides sp.
  • O. multisulcatus
  • O. mirabilis
 Olivooid Medusozoan.
Pseudooides[7][8]
  • Pseudooides sp.
 Medusozoan.
Septuconularia[9][10]
  • S. yanjiaheensis
  • S. crassiformis
 Hexangulaconulariid Medusozoan.
Decimoconularia[11]
  • D. isofacialis
 Hexangulaconulariid Medusozoan.
Carinachites[7][8]
  • C. spinatus
 Cnidarian sclerite, related to the conulariids.
Cambrorhytium[12]
  • C. major
 Elongated cone-like cnidarian.

Chancelloriida

Genus Species Notes Images
Chancelloria[8]
  • Chancelloria sp.
 Sponge-like eumetazoan.

Deuterostome

Genus Species Notes Images
Protohertzina[13][8]
  • P. unguliformis
  • P. anabarica
  • P. robusta
 Possibly a Protoconodont, Paraconodont, or a Chaetognath.
Tarimspira[7]
  • T. plana
 Possible Paraconodont.
Yunnanodus[13][1]
  • Yunnanodus sp.
  • Y. yanjiahensis
 Possible Paraconodont.
Yanjiahella[14]
  • Y. biscarpa
 Ambulacrarian; possibly earliest stem group echinoderm.
Yuknessia[15]
  • Yuknessia sp.
 Unbranched pterobranch.
File:玉溪市博物馆-寒武纪早期-云南澄江-简单约克那斯藻 Yuknessia simplex.jpg
Hertzina[13]
  • H. guizhouensis
  • H. tenuis
 Furnishinid Paraconodont.

Ecdysozoa

Genus Species Notes Images
Beretella[16]
  • B. spinosa
 Possibly adult or larval ecdysozoan.
Saccorhytus[7][8]
  • Saccorhytus sp.
 Possibly adult or larval ecdysozoan.

Lophotrochozoa

Genus Species Notes Images
Conotheca[15][13]
  • C. subcurvata
  • C. obesa
  • C. nana
  • C. transulcata
 Hyolith lophotrochozoan.
Hyolithellus[13]
  • H. tenuis?
  • H. decorus
 Annelid lophotrochozoan, previously thought to be a Hyolith.
Lapworthella[15]
  • Lapworthella sp.
 Tommotid lophotrochozoan.
Spinulitheca[13]
  • S. billingsi
 Hyolith lophotrochozoan.
Microcornus[13]
  • M. parvulus?
 Hyolith lophotrochozoan.
Cupitheca[13]
  • C. mira
 Hyolith lophotrochozoan.
File:Figure S3-166.tif
Turcutheca[13]
  • T. crasseocochlia
  • T. lubrica
 Hyolith lophotrochozoan.
Lophotheca[13]
  • L. costellata
 Hyolith lophotrochozoan.
Circotheca[13][1]
  • C. longiconica
  • C. longiconica
 Circothecid Hyolith.
Aldanella[15][13]
  • A. attleborensis
  • A. yanjiaheensis
 Mollusc with a coiled shell.
Eohalobia[17][7][1]
  • E. diadongensis
  • Eohalobia sp.
 Halkieriid mollusc.
Ocruranus[7][17][8][1]
  • Ocruranus sp.
  • O. trulliformis
  • O. finial
 Halkieriid mollusc.
Scenella[13]
  • S. jijiapoensis
 Scenellid mollusc.
Siphogonuchites[13]
  • S. triangularis
 Siphogonuchitid mollusc.
Xianfengella[13]
  • X. ovata
  • X. prima
 Mollusc.
Tuberoconus[7][1]
  • T. paucipapillae
 Mollusc.
Watsonella[18]
  • W. crosbyi
 Mollusc.
Anabarella[18]
  • A. plana
 Helcionelloid mollusc.
Igorella[13][18]
  • I. emeiensis
  • I. maidipingensis
  • Igorella sp.
 Helcionelloid mollusc.
Oelandiella[13][1]
  • O. korobkovi
 Helcionelloid mollusc.
Ceratoconus[7][1]
  • C. bucers
 Helcionelloid mollusc.

Porifera

Genus Species Notes Images
Blastulospongia[19]
  • Blastulospongia sp.
 Globular demosponge, previously postured to be a radiolarian.

incertae sedis

Genus Species Notes Images
Anabarites[2][13][8]
  • A. trisulcatus
  • A. tianzhushanensis
  • A. gracilis
  • A. ternarius
 Anabaritid small shelly fossil.
Tiksitheca[13]
  • T. korobovi
 Anabaritid small shelly fossil.
Cambrotubulus[7][8]
  • C. decurvatus
 Anabaritid small shelly fossil.
Protoconites[15]
  • P. minor
 Curved conical organism, possible relations to Cnidaria.
File:Protoconites 3D Reconstruction.png
Purella[15][13]
  • P. antiqua
  • P. lepidites
 Small shelly fossil.
Emeiconus[15]
  • E. antiqua
 Small shelly fossil.
Rugatotheca[8]
  • Rugatotheca sp.
 Small shelly fossil.
Coleolella[7]
  • C. recta
 Small shelly fossil.
Vendotaenid[15]
  • Vendotaenia sp.
 Ribbon-like organism.
Torellella[1]
  • T. lentiformis
 Tubicolous fossil.

Flora

Genus Species Notes Images
Archaeophycus[2][20][8]
  • A. yunnanensis
 Either a cyanobacteria or the early developmental stage of an alga.
File:Fossils from the Weng'an biota.jpg
(J)
Konglingiphyton[15]
  • Konglingiphyton sp.
 Macroalgae.
Megathrix[2][21][20]
  • M. longus
 Filamentous cyanobacterium.
Myxococcoides[20]
  • Myxococcoides spp.
 Cyanobacteria.
Archaeooides[8]
  • A. granulates
 Microalgae.

Microorganisms

Genus Species Notes Images
Asteridium[21]
  • A. tornatum
 Acritarch.
Comasphaeridium[2][21]
  • C. annulare
 Acritarch.
Heliosphaeridium[2][21]
  • H. ampliatum
 Acritarch.
Micrhystridium[15]
  • M. regulare
 Acritarch.
Yurtusia[20]
  • Y. uniformis
 Acritarch.
Dictyotidium[20]
  • Dictyotidium sp.?
 Acritarch.

Undescribed

Genus Species Notes Images
Hexactinellid spicules[4]
  • ???
 A collection of monaxons, diaxons and triaxons.
Unnamed probable cnidarian[12]
  • ???
 Curved tubular organism, possible affinities to cnidarians.
Form A[5]
  • ???
 Four specimens with a vermiform morphology that is annulated in appearance, maximum known length is 3.1 mm (0.1 in). Surface ornamentation noted to resemble that seen in the pancrustacean Yicaris from the Yu’anshan Formation, as well as the ecdysozoan Saccorhytus from this formation.
Form B[5]
  • ???
 A singular specimen of a trunk segment covered in spines of varying sizes, maximum length of the specimen is 2.7 mm (0.1 in). Is comparable to various ecdysozoan groups, such as lobopods, and more so to the extant kinorhynchs. It is noted that if the latter interpretation is valid, the specimen would likely be placed as a crown-group kinorhynch, although more evidence is needed.
Form C[5]
  • ???
 The most abundant, with seventeen specimens known, and found in two modes of preservation. Specimens are covered in fractured spines of varying shapes, and the maximum known length of this form being 4.3 mm (0.2 in). Is noted to be comparable to various small shelly fossils such as Protohertzina and Mongolodus, and several ecdysozoans such as Eokinorhynchus, Scalidodendron, and Saccorhytus.
Form D[5]
  • ???
 Two specimens with a vermiform morphology, and is only known to attain a length of 1.8 mm (0.1 in), making it the smallest of the known forms. These specimens have been compared to the likes of Eopriapulites and Palaeoscolex.
Form E[5]
  • ???
 Two specimens, which are evenly covered in small papillate knobs, and attain a maximum known length of 4.9 mm (0.2 in). They have been compared to a wide range of papillate knob-bearing acritarchs, embryos, algae-like forms, and tentative sponges, such as Bacatisphaera, Archaeooides, Shaanisphaera, and Aetholicopalla respectively.
Form F[5]
  • ???
 Five specimens with a dense covering of short coniform to hook-like spines, and are the largest of the forms, attaining a maximum length of 8.9 mm (0.4 in). The five specimens are noted to bear a striking resemblance to Saccorhytus, although they are also notably much larger, suggesting that saccorhytids may have attained much larger sizes than currently known.

See also


References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Liu, Zhanhong; Algeo, Thomas J. (June 2025). "Appearance of SSFs in earliest Cambrian seas of South China linked to salinity conditions". Chemical Geology 683. doi:10.1016/j.chemgeo.2025.122761. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Dong, Lin; Xiao, Shuhai; Shen, Bing; Zhou, Chuanming; Guoxiang, Li; Yao, Jinxian (2009), "Basal Cambrian Microfossils from the Yangtze Gorges Area (South China) and the Aksu Area (Tarim Block, Northwestern China)", Chemical Geology 83 (1): 30–34, doi:10.1666/07-147R.1, Bibcode: 2009JPal...83...30D, http://jpaleontol.geoscienceworld.org/content/83/1/30.abstract, retrieved 2014-08-15 
  3. ↑ 3.0 3.1 Yanjiahe Formation at Fossilworks.org
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Chang, Shan; Feng, Qinglai; Clausen, Sébastien; Zhang, Lei (May 2017). "Sponge spicules from the lower Cambrian in the Yanjiahe Formation, South China: The earliest biomineralizing sponge record". Palaeogeography, Palaeoclimatology, Palaeoecology 474: 36–44. doi:10.1016/j.palaeo.2016.06.032. Bibcode: 2017PPP...474...36C. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Zhang, Lei; Zhai, Fan; Wu, Ying; Chang, Shan; Ye, Yan; Lang, Xianguo; Pang, Yanchun; Hu, Liang et al. (5 June 2026). "Cuticular microfragments from the lower Cambrian Yanjiahe Formation, China: insights into ecdysozoan biodiversity at the dawn of animal radiation". Journal of Micropalaeontology 45 (1): 455–474. doi:10.5194/jm-45-455-2026. Bibcode: 2026JMicP..45..455Z. 
  6. ↑ Guo, Junfeng; Han, Jian; Van Iten, Heyo; Song, Zuchen; Qiang, Yaqin; Wang, Wenzhe; Zhang, Zhifei; Li, Guoxiang et al. (May 2020). "A new tetraradial olivooid (Medusozoa) from the lower Cambrian (Stage 2) Yanjiahe Formation, South China". Journal of Paleontology 94 (3): 457–466. doi:10.1017/jpa.2019.101. Bibcode: 2020JPal...94..457G. 
  7. ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 7.11 Steiner, Michael; Yang, Ben; Hohl, Simon; Zhang, Lei; Chang, Shan (September 2020). "Cambrian small skeletal fossil and carbon isotope records of the southern Huangling Anticline, Hubei (China) and implications for chemostratigraphy of the Yangtze Platform". Palaeogeography, Palaeoclimatology, Palaeoecology 554. doi:10.1016/j.palaeo.2020.109817. Bibcode: 2020PPP...55409817S. 
  8. ↑ 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 8.12 Yang, Lei; Yang, Ben; Shang, Xiaodong; Steiner, Michael (June 2025). "Palaeogeographic and stratigraphic significances of Fortunian small skeletal fossils from the southern Shennongjia Region (China)". Palaeogeography, Palaeoclimatology, Palaeoecology 668. doi:10.1016/j.palaeo.2025.112910. Bibcode: 2025PPP...66812910Y. 
  9. ↑ Guo, Junfeng; Han, Jian; Iten, Heyo Van; Wang, Xing; Qiang, Yaqin; Song, Zuchen; Wang, Wenzhe; Zhang, Zhifei et al. (January 2020). "A fourteen-faced hexangulaconulariid from the early Cambrian (Stage 2) Yanjiahe Formation, South China". Journal of Paleontology 94 (1): 45–55. doi:10.1017/jpa.2019.56. Bibcode: 2020JPal...94...45G. 
  10. ↑ Song, Zuchen; Guo, Junfeng; Han, Jian; Van Iten, Heyo; Qiang, Yaqin; Peng, Jiaxin; Sun, Jie; Zhang, Zhifei (June 2022). "A New Species of Septuconularia (Hexangulaconulariidae, Cnidaria) from Cambrian Stage 2, South China". Acta Geologica Sinica - English Edition 96 (3): 757–765. doi:10.1111/1755-6724.14917. Bibcode: 2022AcGlS..96..757S. 
  11. ↑ Guo, Junfeng; Han, Jian; Van Iten, Heyo; Song, Zuchen; Qiang, Yaqin; Wang, Wenzhe; Zhang, Zhifei; Li, Guoxiang (September 2021). "A ten-faced hexangulaconulariid from Cambrian Stage 2 of South China". Journal of Paleontology 95 (5): 957–964. doi:10.1017/jpa.2021.25. Bibcode: 2021JPal...95..957G. 
  12. ↑ 12.0 12.1 Chang, Shan; Clausen, Sébastien; Zhang, Lei; Feng, Qinglai; Steiner, Michael; Bottjer, David J.; Zhang, Yan; Shi, Min (September 2018). "New probable cnidarian fossils from the lower Cambrian of the Three Gorges area, South China, and their ecological implications". Palaeogeography, Palaeoclimatology, Palaeoecology 505: 150–166. doi:10.1016/j.palaeo.2018.05.039. Bibcode: 2018PPP...505..150C. 
  13. ↑ 13.00 13.01 13.02 13.03 13.04 13.05 13.06 13.07 13.08 13.09 13.10 13.11 13.12 13.13 13.14 13.15 13.16 13.17 13.18 13.19 Guo, Junfeng; Li, Yong; Li, Guoxiang (April 2014). "Small shelly fossils from the early Cambrian Yanjiahe Formation, Yichang, Hubei, China". Gondwana Research 25 (3): 999–1007. doi:10.1016/j.gr.2013.03.007. Bibcode: 2014GondR..25..999G. 
  14. ↑ Topper, Timothy P.; Guo, Junfeng; Clausen, Sébastien; Skovsted, Christian B.; Zhang, Zhifei (2019), "A stem group echinoderm from the basal Cambrian of China and the origins of Ambulacraria", Nature Communications 10 (1): 1366, doi:10.1038/s41467-019-09059-3, ISSN 2041-1723, PMID 30911013, Bibcode: 2019NatCo..10.1366T 
  15. ↑ 15.00 15.01 15.02 15.03 15.04 15.05 15.06 15.07 15.08 15.09 Guo, J.; Li, Y.; Han, J.; Zhang, X.; Zhang, Z.; Ou, Q.; Liu, J.; Shu, D. et al. (2008), "Fossil association from the Lower Cambrian Yanjiahe Formation in the Yangtze Gorges area, Hubei, south China", Acta Geologica Sinica 82 (6): 1124–1132, doi:10.1111/j.1755-6724.2008.tb00712.x, Bibcode: 2008AcGlS..82.1124G 
  16. ↑ Wang, Deng; Qiang, Yaqin; Guo, Junfeng; Vannier, Jean; Song, Zuchen; Peng, Jiaxin; Zhang, Boyao; Sun, Jie et al. (2024-02-19). Early evolution of the ecdysozoan body plan (Report). doi:10.7554/elife.94709.1. https://elifesciences.org/reviewed-preprints/94709v1. 
  17. ↑ 17.0 17.1 Song, Zuchen; Guo, Junfeng; Pan, Bing; Qiang, Yaqin; Li, Guoxiang; Peng, Jiaxin; Sun, Jie; Han, Jian (11 November 2022). "Ocruranus–Eohalobia Sclerites from the Cambrian Stage 2 Yanjiahe Formation in South China: Scleritome Reconstruction and Zoological Affinity". Biology 11 (11): 1648. doi:10.3390/biology11111648. PMID 36421362. 
  18. ↑ 18.0 18.1 18.2 Qiang, Yaqin; Peng, Jiaxin; Song, Zuchen; Sun, Jie; Zhao, Xiaofang; Li, Guoxiang; Han, Jian; Guo, Junfeng (17 January 2023). "Early Cambrian Anabarella plana from Three Gorges area, South China". Frontiers in Earth Science 10. doi:10.3389/feart.2022.1074000. Bibcode: 2023FrEaS..1074000Q. 
  19. ↑ Chang, Shan; Feng, Qinglai; Zhang, Lei (August 2018). "New Siliceous Microfossils from the Terreneuvian Yanjiahe Formation, South China: The Possible Earliest Radiolarian Fossil Record". Journal of Earth Science 29 (4): 912–919. doi:10.1007/s12583-017-0960-0. Bibcode: 2018JEaSc..29..912C. 
  20. ↑ 20.0 20.1 20.2 20.3 20.4 Chang, Shan; Zhang, Lei; Feng, Qinglai (September 2025). "Diverse organic-walled microfossils from the basal Cambrian Yanjiahe Formation in the eastern Three Gorges area". Review of Palaeobotany and Palynology 340. doi:10.1016/j.revpalbo.2025.105361. Bibcode: 2025RPaPa.34005361C. 
  21. ↑ 21.0 21.1 21.2 21.3 Ahn, Soo Yeun; Zhu, Maoyan (November 2017). "Lowermost Cambrian acritarchs from the Yanjiahe Formation, South China: implication for defining the base of the Cambrian in the Yangtze Platform". Geological Magazine 154 (6): 1217–1231. doi:10.1017/S0016756816001369. Bibcode: 2017GeoM..154.1217A. 

Further reading

  • P. Chen. 1984. Discovery of Lower Cambrian small shelly fossils from Jijiapo, Yichang, west Hubei and its significance. Professional Papers of Stratigraphy and Palaeontology 13:49-64



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