Orbisiana
{{Automatic taxobox
| fossil_range = Ediacaran
| image =
| image_caption =
| taxon = Orbisiana
| authority = Sokolov, 1976
| subdivision_ranks = Species
| subdivision =
- O. simplex Sokolov, 1976
- O. linearis (Chen, 1994)
}}
Orbisiana is an Ediacaran benthic organism formed out of series of agglutinated spherical or hemispherical chambers. It is believed to be a close relative of Palaeopascichnus.{{citation needed|date=April 2022}}
Description
Orbisiana occur in aggregates made up of rows arranged in sometimes branching chains.{{Cite journal | doi=10.1016/j.precamres.2018.08.011 |title = A reassessment of the problematic Ediacaran genus Orbisiana Sokolov 1976|journal = Precambrian Research|volume = 316|pages = 197–205|year = 2018|last1 = Kolesnikov|first1 = Anton V.|last2 = Liu|first2 = Alexander G.|last3 = Danelian|first3 = Taniel|last4 = Grazhdankin|first4 = Dmitriy V.|bibcode = 2018PreR..316..197K|s2cid = 134213721|url = https://www.repository.cam.ac.uk/handle/1810/285052}} 3-D analysis has shown Orbisiana to be cylindrical in shape and open at both the top and bottom ends of its structure.{{Cite journal|last1=Wan|first1=Bin|last2=Xiao|first2=Shuhai|last3=Yuan|first3=Xunlai|last4=Chen|first4=Zhe|last5=Pang|first5=Ke|last6=Tang|first6=Qing|last7=Guan|first7=Chengguo|last8=Maisano|first8=Jessica A.|title=Orbisiana linearis from the early Ediacaran Lantian Formation of South China and its taphonomic and ecological implications|journal=Precambrian Research|volume=255|pages=266–275|doi=10.1016/j.precamres.2014.09.028|year=2014|bibcode=2014PreR..255..266W}} The chains often varied in shape from straight to curved and disorganized lines of spheres with no fixed number of spheres per chain. Specimens range in size but generally have diameters of {{convert|0.2|-|0.9|mm|in}}.{{Cite journal|last=Jensen|first=Sören|date=2003|title=The Proterozoic and Earliest Cambrian Trace Fossil Record; Patterns, Problems and Perspectives|journal=Integrative and Comparative Biology|volume=43|issue=1|pages=219–228|doi=10.1093/icb/43.1.219|pmid=21680425|issn=1540-7063|doi-access=free}} The cell membranes of the organism are often pyritized.{{Cite journal|last=Sokolov|first=B. S.|date=1976|title=The Earth's organic world on the path toward Phanerozoic differentiation|journal=Vestn. Akademiya Nauk|volume=1|pages=126–143}} The individual chambers are agglutinating.{{Cite journal|doi = 10.1016/j.precamres.2018.08.011|title = A reassessment of the problematic Ediacaran genus Orbisiana Sokolov 1976|journal = Precambrian Research|volume = 316|pages = 197–205|year = 2018|last1 = Kolesnikov|first1 = Anton V|last2 = Liu|first2 = Alexander G|last3 = Danelian|first3 = Taniel|last4 = Grazhdankin|first4 = Dmitriy V|bibcode = 2018PreR..316..197K|s2cid = 134213721|url = https://www.repository.cam.ac.uk/handle/1810/285052}}
Diversity
Two species have been documented, O. linearis and O. simplex.{{Cite journal|last1=Fedonkin|first1=M. A.|last2=Simonetta|first2=A.|last3=Ivantsov|first3=A. Y.|title=New data on Kimberella, the Vendian mollusc-like organism (White Sea region, Russia): palaeoecological and evolutionary implications|journal=Geological Society, London, Special Publications|volume=286|issue=1|pages=157–179|doi=10.1144/sp286.12|year=2007|bibcode=2007GSLSP.286..157F|s2cid=331187}}{{Cite book|title=Neoproterozoic Geobiology and Paleobiology|last1=Xiao|first1=Shuhai|last2=Dong|first2=Lin|date=2006|publisher=Springer, Dordrecht|isbn=9781402052019|series=Topics in Geobiology|pages=57–90|language=en|doi=10.1007/1-4020-5202-2_3}}
It fits into the Palaeopascichnids, the other genus being Palaeopascichnus itself.{{Cite journal | doi=10.1016/j.precamres.2018.08.011 |title = A reassessment of the problematic Ediacaran genus Orbisiana Sokolov 1976|journal = Precambrian Research|volume = 316|pages = 197–205|year = 2018|last1 = Kolesnikov|first1 = Anton V.|last2 = Liu|first2 = Alexander G.|last3 = Danelian|first3 = Taniel|last4 = Grazhdankin|first4 = Dmitriy V.|bibcode = 2018PreR..316..197K|s2cid = 134213721|url = https://www.repository.cam.ac.uk/handle/1810/285052}}
= Distribution =
Over 100 specimens have been collected from the lower Ediacaran Lantian Formation located in Xiuning and Yixian counties of the Anhui Province, China.
Discovery
Orbisiana was first described by B.S. Sokolov in 1976, found in the Neoproterozoic of Russia.