Yunnanozoon lividum (Yunnan + Greek ζῷον zôion (animal), with species name Latin lividum; (lead-coloured), referring to preserved colour of specimens[1]) is an extinct species of bilaterian animal from the Lower CambrianChengjiang biota of Yunnan province, China. Its affinities have been long the subject of controversy.
Well preserved specimen and diagram of body anatomy
The body of Yunnanozoon was fusiform, with specimens ranging from 2 to 6 centimetres (0.79 to 2.36 in) in length. The body was strongly laterally compressed, meaning that it was taller than it was wide. A segmented dorsal unit was present on the top of the body. The first segment of which was triangular, while the other segments were approximately rectangular. Axial stripes also ran down the body in the region immediately below the dorsal unit. Towards the front of the animal were 7 pairs of filamentous arches. These arches were covered by sac-like structures which had openings between them. Towards the back of the body a tube-like structure was present, possibly the gut, with four pairs of enigmatic circular structures (possibly gonads) were present at the mid-point of the body. The front half of the body had rod-like structures running along the top and bottom, which were probably sclerotized.[2]
Taxonomyedit
Yunnanozoon was described by Hou, Ramskold & Bergstrom in 1991, who considered its placement to be incertae sedis within Metazoa.[1] The placement of Yunnanozoon has been controversial, with various studies suggesting placements as a cephalochordate, a stem-chordate, a hemichordate, a stem-vertebrate, a stem-deuterostome, an ambulacrarian, a bilaterian of uncertain placement, as a protosome of uncertain position, or a relative of Ecdysozoa.[2] A 2015 study which comprehensively described Yunnanozoon considered it a member of Bilateria of uncertain placement.[2] A 2022 study of the filamentous arches using advanced imaging techniques suggested that they were "composed of cartilage within an extracellular matrix of micofibrils", suggesting that yunannozoans were stem-vertebrates.[3]
In 1995, Jerzy Dzik placed Yunannozoon into its own class, Yunnanozoa.[4] In 1999, another genus of yunnanozoan, Haikouella described from the same deposits as Yannonzoon, with the species Haikouella lanceolata.[5] A second species of the genus Haikouella jianshanensis was described in 2003.[6] The describers of Haikouella distinguished it from Yunnanozoon based on the number of filamentous arches and circular structures, and the placement of structure proposed to be pharyngeal teeth. However a comprehensive study of yunnanozoans in 2015 found that the number of filamentous arches and circular structures were the same in all yunnanozoans examined and that the supposed "pharyngeal teeth" were instead remnants of other structures, suggesting that there was only one species, Yunnanozoon lividum, with both Haikouella species being junior synonyms of it.[2]
Ecologyedit
Yunannozoon is suggested to have used its filamentous arches to feed with the openings on the side of the body being used to expel water.[2]
^ abXianguang, Hou; RamsköLd, Lars; BergströM, Jan (October 1991). "Composition and preservation of the Chengjiang fauna –a Lower Cambrian soft‐bodied biota". Zoologica Scripta. 20 (4): 395–411. doi:10.1111/j.1463-6409.1991.tb00303.x. ISSN 0300-3256.
^ abcdeCong, Pei-Yun; Hou, Xian-Guang; Aldridge, Richard J.; Purnell, Mark A.; Li, Yi-Zhen (2015). Smith, Andrew (ed.). "New data on the palaeobiology of the enigmatic yunnanozoans from the Chengjiang Biota, Lower Cambrian, China". Palaeontology. 58 (1): 45–70. doi:10.1111/pala.12117. S2CID 84567733.
^Shu, Degan; Morris, Simon Conway; Zhang, Z. F.; Liu, J. N.; Han, Jian; Chen, Ling; Zhang, X. L.; Yasui, K.; Li, Yong (28 February 2003). "A New Species of Yunnanozoan with Implications for Deuterostome Evolution". Science. 299 (5611): 1380–1384. doi:10.1126/science.1079846. ISSN 0036-8075.
External linksedit
A picture can be found at
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yunnanozoon, confused, with, yuyuanozoon, lividum, yunnan, greek, ζῷον, zôion, animal, with, species, name, latin, lividum, lead, coloured, referring, preserved, colour, specimens, extinct, species, bilaterian, animal, from, lower, cambrian, chengjiang, biota,. Not to be confused with Yuyuanozoon Yunnanozoon lividum Yunnan Greek zῷon zoion animal with species name Latin lividum lead coloured referring to preserved colour of specimens 1 is an extinct species of bilaterian animal from the Lower Cambrian Chengjiang biota of Yunnan province China Its affinities have been long the subject of controversy YunnanozoonTemporal range Terreneuvian 525 Ma PreꞒ Ꞓ O S D C P T J K Pg N A fossil of Yunnanozoon lividum Scientific classification Domain Eukaryota Kingdom Animalia Family YunnanozoonidaeDzik 1995 Genus YunnanozoonHou Ramskold amp Bergstrom 1991 Species Y lividum Binomial name Yunnanozoon lividumHou Ramskold amp Bergstrom 1991 Synonyms Haikouella Chen Huang amp Li 1999 Contents 1 Description 2 Taxonomy 3 Ecology 4 See also 5 References 6 External linksDescription edit nbsp Well preserved specimen and diagram of body anatomy The body of Yunnanozoon was fusiform with specimens ranging from 2 to 6 centimetres 0 79 to 2 36 in in length The body was strongly laterally compressed meaning that it was taller than it was wide A segmented dorsal unit was present on the top of the body The first segment of which was triangular while the other segments were approximately rectangular Axial stripes also ran down the body in the region immediately below the dorsal unit Towards the front of the animal were 7 pairs of filamentous arches These arches were covered by sac like structures which had openings between them Towards the back of the body a tube like structure was present possibly the gut with four pairs of enigmatic circular structures possibly gonads were present at the mid point of the body The front half of the body had rod like structures running along the top and bottom which were probably sclerotized 2 Taxonomy editYunnanozoon was described by Hou Ramskold amp Bergstrom in 1991 who considered its placement to be incertae sedis within Metazoa 1 The placement of Yunnanozoon has been controversial with various studies suggesting placements as a cephalochordate a stem chordate a hemichordate a stem vertebrate a stem deuterostome an ambulacrarian a bilaterian of uncertain placement as a protosome of uncertain position or a relative of Ecdysozoa 2 A 2015 study which comprehensively described Yunnanozoon considered it a member of Bilateria of uncertain placement 2 A 2022 study of the filamentous arches using advanced imaging techniques suggested that they were composed of cartilage within an extracellular matrix of micofibrils suggesting that yunannozoans were stem vertebrates 3 In 1995 Jerzy Dzik placed Yunannozoon into its own class Yunnanozoa 4 In 1999 another genus of yunnanozoan Haikouella described from the same deposits as Yannonzoon with the species Haikouella lanceolata 5 A second species of the genus Haikouella jianshanensis was described in 2003 6 The describers of Haikouella distinguished it from Yunnanozoon based on the number of filamentous arches and circular structures and the placement of structure proposed to be pharyngeal teeth However a comprehensive study of yunnanozoans in 2015 found that the number of filamentous arches and circular structures were the same in all yunnanozoans examined and that the supposed pharyngeal teeth were instead remnants of other structures suggesting that there was only one species Yunnanozoon lividum with both Haikouella species being junior synonyms of it 2 Ecology editYunannozoon is suggested to have used its filamentous arches to feed with the openings on the side of the body being used to expel water 2 See also editMetaspriggina PikaiaReferences edit a b Xianguang Hou RamskoLd Lars BergstroM Jan October 1991 Composition and preservation of the Chengjiang fauna a Lower Cambrian soft bodied biota Zoologica Scripta 20 4 395 411 doi 10 1111 j 1463 6409 1991 tb00303 x ISSN 0300 3256 a b c d e Cong Pei Yun Hou Xian Guang Aldridge Richard J Purnell Mark A Li Yi Zhen 2015 Smith Andrew ed New data on the palaeobiology of the enigmatic yunnanozoans from the Chengjiang Biota Lower Cambrian China Palaeontology 58 1 45 70 doi 10 1111 pala 12117 S2CID 84567733 Tian Qingyi Zhao Fangchen Zeng Han Zhu Maoyan Jiang Baoyu 8 July 2022 Ultrastructure reveals ancestral vertebrate pharyngeal skeleton in yunnanozoans Science 377 6602 218 222 Bibcode 2022Sci 377 218T doi 10 1126 science abm2708 ISSN 0036 8075 PMID 35857544 S2CID 250380981 Yunnantozoon and the ancestry of chordates Acta Palaeontologica Polonica www app pan pl Retrieved 11 February 2024 Chen Jun Yuan Huang Di Ying Li Chia Wei December 1999 An early Cambrian craniate like chordate Nature 402 6761 518 522 doi 10 1038 990080 ISSN 0028 0836 Shu Degan Morris Simon Conway Zhang Z F Liu J N Han Jian Chen Ling Zhang X L Yasui K Li Yong 28 February 2003 A New Species of Yunnanozoan with Implications for Deuterostome Evolution Science 299 5611 1380 1384 doi 10 1126 science 1079846 ISSN 0036 8075 External links editA picture can be found at https web archive org web 20030511135309 http www gs rc org 80 repo repoe htm nbsp This chordate related article is a stub You can help Wikipedia by expanding it vte nbsp This article related to a Cambrian animal is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Yunnanozoon amp oldid 1217176936, wikipedia, wiki, book, books, library,
