Tsunyidiscus is a trilobite belonging to the Suborder Eodiscina. Tsunyidiscus appeared near the end of the Lower Cambrian, during the late Atdabanian stage of geologic time and some collections suggest it may have survived into the Botomian. The genus is very small (up to 7mm), oculate and isopypous with a narrow dome-shaped glabella and a narrow bullet-shaped pygidial axis. Thorax consists of three segments. Tsunyidiscus is the only genus currently attributed to the family Tsunyidiscidae.[1]
Like other Agnostida the exoskeleton of Tsunyidiscus is diminutive and isopygous with 3 fulcrate thoracic segments. The cephalon has a strongly parabolic outline and maximum width (tr.) usually anterior to the genal angles. Glabella extremely narrow, lateral glabellar furrows usually obscure, with a rounded and expanded frontal glabellar lobe. The occipital ring (LO) is at least as long as L1, usually expanded laterally, and may bear a sharp posteriorly directed spine. Long, curved posterior fixigenal spines may be present. The occipital furrow is transverse and uninterrupted. Facial sutures proparian. Librigenae are 0.5% as long as the cephalon. The pygidium has a narrow multi=segmented axis (with five, six or more segments). The thoracic and pygidial axial segments may carry nodes.[1][2]
Species and distributionedit
Tsunyidiscus aclis (Zhou, 1975)
=Emeidiscus planilimbatus, Mianxiandiscus badaowanensis, M. emeiensis, M. gaoqiaoensis, M. jinningensis, M. sichuanensis
Collected in the Lower Cambrian of China (Atdabanian: Jinning, 24.7° N, 102.7° E[3] and Maotianshan 24.0°N, 102.0°E,[4] Yuanshan Formation, Yunnan).
Tsunyidiscus acutus (Sun, 1983)
Present in the Lower Cambrian of China (Atdabanian, Shuijingtuo Formation, Yichang and Zgui, Yangtze Gorge Area, Hubei, 111°E, 30.5°N)[2]
Tsunyidiscus armatus (Zhang & Zhu, 1980)
Occurs in the Lower Cambrian of China (Atdabanian: Weng'an, Longshancun Section, Niutitang Formation, Guizhou, 27.1°N, 107.5°E)[3]
Tsunyidiscus chintingshanensis (Lu, 1942)
=T. kaiyangensis, Eodiscus chintingshanensis, Guizhoudiscus chintingshanensis, G. kaiyangensis, H. chintingshanensis
Occurs in the Lower Cambrian of China (Zhongxin).[5]
Tsunyidiscus limbanodus Qian in Zhang et al., 1980
Tsunyidiscus longquanensis (Zhang and Zhu in Zhang et al., 1980)
Known from the Lower Cambrian of China (Atdabanian: Jinning, 24.7° N, 102.7° E[3] and Malong, 25.4° N, 103.4° E,[6] Yuanshan Formation, Yunnan; Zhijin, Gezhongwu Section,[3] and Weng'an, Longshancun Section, Niutitang Formation, GuiZhou, 26.7°N, 105.8°E.
Tsunyidiscus pengshuiensis Zhang & Clarkson, 2012 was extracted from the Lower Cambrian of China (Qiongzhusi Formation).[7]
Tsunyidiscus pertenus Lin et al., 2004
=T. orientalis, Hebediscus orientalis, Hupeidiscus orientalis
Found in the Lower Cambrian of China (Atdabanian: Huanglian Member, Jiumenchong Formation, 28.2°N, 109.2°E, Taijiang, Wuhe Member, Jiumenchong and Bianmachong Formations, 26.7° N, 108.3° E);[3] Botomian: Weng'an, Longshancun Section, Mingxinsi Formation, Guizhou, 27.1°N, 107.5°E;[3] Atdabanian: Pangwangcun Member, Huangboling Formation, Anhui, 30.1°N, 117.0°E[3]
Tsunyidiscus yanjiazhiensis S. Zang et al. in Yin and Li, 1978
Tsunyidiscus sp.
Present in the Lower Cambrian of China (Atdabanian: Shuijingtuo Formation, Yangtze Gorge, Hubei, 30.8° N, 111.3° E).[8]
Taxonomyedit
Cladogram of the relations within the monotypical family Tsunyidiscidae, with other Eodiscina and with the ancestral genus Bulaiaspis (Redlichiina, Chengkouaspidae)[9]
Ancestorsedit
Tsunyidiscus is the oldest known eodiscoid. The glabella of Tsunyidiscus is extremely similar to that of Dipharus clarki, and distinct from all other eodiscoids. D. clarki is thought to represent an immature stage of the redlichioid Bulaiaspis rather than an eodiscoid. This is because of the dominant palpebroocular ridges, extremely long librigenae, and free pleural tips on the pygidium of variable numbers of segments. In short: Tsunyidiscus is thought to have developed through paedomorphosis from Bulaiaspis.[1]
Descendantsedit
Three lineages are thought to have evolved from Tsunyidiscus. First the Hebediscidae, that themselves gave rise to the Weymouthiidae, which contain Tannudiscus, the probable ancestor of the Agnostina. Second the Yukoniidae, who sprouted the Eodiscidae. And finally the Calodiscidae.[1]
Referencesedit
^ abcdWhittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997
^ abDai, T.; Zhan, X. (2011). "Ontogeny of the eodiscoid trilobite Tsunydiscus acutus from the Lower Cambrian of South China". Palaeontology. 54 (6): 1279–1288. Bibcode:2011Palgy..54.1279D. doi:10.1111/j.1475-4983.2011.01102.x. ISSN 0031-0239.
^ abcdefgA. Yang, M. Zhu, J. Zhang and G. Li. 2003. Early Cambrian eodiscoid trilobites of the Yangtze Platform and their stratigraphic implications. Progress in Natural Science 13(11):861-866 |cited in=PBDB
^J. Yugan, H. Xianguang, and W. Huayu. 1993. Lower Cambrian pediculate lingulids from Yunnan, China. Journal of Paleontology 67(5):788-798|cited in=PBDB
^Paleobiology Database. "†Tsunyidiscus chintingshanensis Lu 1942 (trilobite)". Retrieved 25 November 2012.
^M. Steiner, M. Zhu, Y. Zhao and B.-D. Erdtmann. 2005. Lower Cambrian Burgess Shale-type fossil associations of South China. Palaeogeography, Palaeoclimatology, Palaeoecology 220:129-152|cited in=PBDB
^Zhang, X.-G.; Clarkson, E.N.K. (2012). "Phosphatized eodiscoid trilobites from the Cambrian of China". Palaeontographica Abteilung A. 297 (1–4): 1–121. Bibcode:2012PalAA.297....1Z. doi:10.1127/pala/297/2012/1. Archived from the original on 2013-02-11.
^S. Weiguo. 1986. Late Precambrian Pennatulids (sea pens) from the Eastern Yangtze Gorge, China: Paracharnia gen. nov Precambrian Research 31:361-375|cited in=PBDB
^Cotton, T.J.; Fortey, R.A. (2005). "5. Comparative morphology and relationships of the Agnostida". In Koenemann, S.; Jenner, R. (eds.). Crustacean Issues 16, Crustacea and Arthropod Relationships. Boca Raton: CRC Press.
January 01, 1970
tsunyidiscus, trilobite, belonging, suborder, eodiscina, appeared, near, lower, cambrian, during, late, atdabanian, stage, geologic, time, some, collections, suggest, have, survived, into, botomian, genus, very, small, oculate, isopypous, with, narrow, dome, s. Tsunyidiscus is a trilobite belonging to the Suborder Eodiscina Tsunyidiscus appeared near the end of the Lower Cambrian during the late Atdabanian stage of geologic time and some collections suggest it may have survived into the Botomian The genus is very small up to 7mm oculate and isopypous with a narrow dome shaped glabella and a narrow bullet shaped pygidial axis Thorax consists of three segments Tsunyidiscus is the only genus currently attributed to the family Tsunyidiscidae 1 TsunyidiscusTemporal range Late Atdabanian PreꞒ Ꞓ O S D C P T J K Pg N linedrawing of Tsunyidiscus niutitangensis Scientific classification Kingdom Animalia Phylum Arthropoda Class Trilobita Order Agnostida Suborder Eodiscina Family TsunyidiscidaeZhang 1980 Genus TsunyidiscusW Chang 1966 Species T niutitangensis Chang 1964 Type T aclis Zhou 1975 T acutus Sun 1983 T armatus Zhang amp Zhu 1980 T chintingshanensis Lu 1942 T limbanodus Qian in Zhang et al 1980 T longquanensis Zhang and Zhu in Zhang et al 1980 T pengshuiensis Zhang amp Clarkson 2012 T pertenus Lin et al 2004 T yanjiazhiensis S Zang et al in Yin and Li 1978 And see text Contents 1 Description 2 Species and distribution 3 Taxonomy 3 1 Ancestors 3 2 Descendants 4 ReferencesDescription editLike other Agnostida the exoskeleton of Tsunyidiscus is diminutive and isopygous with 3 fulcrate thoracic segments The cephalon has a strongly parabolic outline and maximum width tr usually anterior to the genal angles Glabella extremely narrow lateral glabellar furrows usually obscure with a rounded and expanded frontal glabellar lobe The occipital ring LO is at least as long as L1 usually expanded laterally and may bear a sharp posteriorly directed spine Long curved posterior fixigenal spines may be present The occipital furrow is transverse and uninterrupted Facial sutures proparian Librigenae are 0 5 as long as the cephalon The pygidium has a narrow multi segmented axis with five six or more segments The thoracic and pygidial axial segments may carry nodes 1 2 Species and distribution editTsunyidiscus aclis Zhou 1975 Emeidiscus planilimbatus Mianxiandiscus badaowanensis M emeiensis M gaoqiaoensis M jinningensis M sichuanensis dd Collected in the Lower Cambrian of China Atdabanian Jinning 24 7 N 102 7 E 3 and Maotianshan 24 0 N 102 0 E 4 Yuanshan Formation Yunnan Tsunyidiscus acutus Sun 1983 Present in the Lower Cambrian of China Atdabanian Shuijingtuo Formation Yichang and Zgui Yangtze Gorge Area Hubei 111 E 30 5 N 2 Tsunyidiscus armatus Zhang amp Zhu 1980 Occurs in the Lower Cambrian of China Atdabanian Weng an Longshancun Section Niutitang Formation Guizhou 27 1 N 107 5 E 3 Tsunyidiscus chintingshanensis Lu 1942 T kaiyangensis Eodiscus chintingshanensis Guizhoudiscus chintingshanensis G kaiyangensis H chintingshanensis dd Occurs in the Lower Cambrian of China Zhongxin 5 Tsunyidiscus limbanodus Qian in Zhang et al 1980 Tsunyidiscus longquanensis Zhang and Zhu in Zhang et al 1980 Shizhudiscus longquanensis dd Tsunyidiscus niutitangensis Chang 1964 Hebediscus niutitangensis dd Known from the Lower Cambrian of China Atdabanian Jinning 24 7 N 102 7 E 3 and Malong 25 4 N 103 4 E 6 Yuanshan Formation Yunnan Zhijin Gezhongwu Section 3 and Weng an Longshancun Section Niutitang Formation GuiZhou 26 7 N 105 8 E Tsunyidiscus pengshuiensis Zhang amp Clarkson 2012 was extracted from the Lower Cambrian of China Qiongzhusi Formation 7 Tsunyidiscus pertenus Lin et al 2004 T orientalis Hebediscus orientalis Hupeidiscus orientalis dd Found in the Lower Cambrian of China Atdabanian Huanglian Member Jiumenchong Formation 28 2 N 109 2 E Taijiang Wuhe Member Jiumenchong and Bianmachong Formations 26 7 N 108 3 E 3 Botomian Weng an Longshancun Section Mingxinsi Formation Guizhou 27 1 N 107 5 E 3 Atdabanian Pangwangcun Member Huangboling Formation Anhui 30 1 N 117 0 E 3 Tsunyidiscus yanjiazhiensis S Zang et al in Yin and Li 1978 Tsunyidiscus sp Present in the Lower Cambrian of China Atdabanian Shuijingtuo Formation Yangtze Gorge Hubei 30 8 N 111 3 E 8 Taxonomy edit nbsp Cladogram of the relations within the monotypical family Tsunyidiscidae with other Eodiscina and with the ancestral genus Bulaiaspis Redlichiina Chengkouaspidae 9 Ancestors edit Tsunyidiscus is the oldest known eodiscoid The glabella of Tsunyidiscus is extremely similar to that of Dipharus clarki and distinct from all other eodiscoids D clarki is thought to represent an immature stage of the redlichioid Bulaiaspis rather than an eodiscoid This is because of the dominant palpebroocular ridges extremely long librigenae and free pleural tips on the pygidium of variable numbers of segments In short Tsunyidiscus is thought to have developed through paedomorphosis from Bulaiaspis 1 Descendants edit Three lineages are thought to have evolved from Tsunyidiscus First the Hebediscidae that themselves gave rise to the Weymouthiidae which contain Tannudiscus the probable ancestor of the Agnostina Second the Yukoniidae who sprouted the Eodiscidae And finally the Calodiscidae 1 References edit a b c d Whittington H B et al Part O Treatise on Invertebrate Paleontology Revised Volume 1 Trilobita Introduction Order Agnostida Order Redlichiida 1997 a b Dai T Zhan X 2011 Ontogeny of the eodiscoid trilobite Tsunydiscus acutus from the Lower Cambrian of South China Palaeontology 54 6 1279 1288 Bibcode 2011Palgy 54 1279D doi 10 1111 j 1475 4983 2011 01102 x ISSN 0031 0239 a b c d e f g A Yang M Zhu J Zhang and G Li 2003 Early Cambrian eodiscoid trilobites of the Yangtze Platform and their stratigraphic implications Progress in Natural Science 13 11 861 866 cited in PBDB J Yugan H Xianguang and W Huayu 1993 Lower Cambrian pediculate lingulids from Yunnan China Journal of Paleontology 67 5 788 798 cited in PBDB Paleobiology Database Tsunyidiscus chintingshanensis Lu 1942 trilobite Retrieved 25 November 2012 M Steiner M Zhu Y Zhao and B D Erdtmann 2005 Lower Cambrian Burgess Shale type fossil associations of South China Palaeogeography Palaeoclimatology Palaeoecology 220 129 152 cited in PBDB Zhang X G Clarkson E N K 2012 Phosphatized eodiscoid trilobites from the Cambrian of China Palaeontographica Abteilung A 297 1 4 1 121 Bibcode 2012PalAA 297 1Z doi 10 1127 pala 297 2012 1 Archived from the original on 2013 02 11 S Weiguo 1986 Late Precambrian Pennatulids sea pens from the Eastern Yangtze Gorge China Paracharnia gen nov Precambrian Research 31 361 375 cited in PBDB Cotton T J Fortey R A 2005 5 Comparative morphology and relationships of the Agnostida In Koenemann S Jenner R eds Crustacean Issues 16 Crustacea and Arthropod Relationships Boca Raton CRC Press Retrieved from https en wikipedia org w index php title Tsunyidiscus amp oldid 1186445339, wikipedia, wiki, book, books, library,
