Size comparison of Sidneyia speciesBiramous limb of Sidneyia inexpectans Key: gnathobasic basipod (pink, labelled pr) exopod (yellow, labelled ex), endopod (orange, with terminal podomere labelled pd7 in yellow)
Sidneyia inexpectans reached lengths of at least 160 millimetres (6.3 in).[1] The largest known specimen of S. minor is around 23 mm (0.91 in) long and 14 mm (0.55 in) wide,[2] while the largest specimen of S. malongensis is 31 mm (1.2 in) long and 21 mm (0.83 in) wide.[3] The head shield is short, with notches present on the sides to accommodate stalked eyes, with the underside having a hypostome. The head has a pair of segmented antennae, as well as three pairs of post-antenal appendages. This was followed by a thorax, which had eight to ten segments/tergites, each associated with a pair of biramous appendages, this was followed with one to three abdomen segments/tergites, with the body terminating with a telson, which comprised a pair of tail flukes.[2][3] The appendages bear heavily sclerotised spined basal segments (basipods) called gnathobases, used to process food.[2][1][4] In S. minor, the biramous appendages have 8 podomeres/segments on the endopod, with the last segment being a terminal claw. The exopod of these limbs is flattened and bears lamellae.[2] In S. inexpectans, the endopods of the biramous limbs have seven podomeres, with the first four of these each bearing a number of thin inward projecting spines, while the outer three podomeres bore more stout claw-like spines, with the fourth to ninth pairs of post antennal limbs bearing exopods with blade-like lamellae, which are thought to have been used as gills.[1]S. inexpectans had three pairs of digestive glands within the head shield and front of the thorax, adjacent to the central gut tube.[1]
Ecologyedit
Sidneyia is thought to have been seafloor dwelling (epibenthic) generalist durophagous predator and/or scavenger that used its gnathobases (which closely resemble those of horseshoe crabs) to crush and shred prey items, including hard-shelled organisms like juvenile trilobites (which are abundantly preserved as stomach contents in S. inexpectans) and brachiopods (representing around 6% of the stomach contents of S. inexpectans), but possibly also softer animals like worms or soft bodied arthropods like bradoriids.[1][5]
Taxonomyedit
Sidneyia was discovered in 1910 during the first day of Charles Walcott's exploration of the Burgess Shale. He named it after his elder son, Sidney, who had helped to locate the site and collect the specimen. The species name, Sidneyia inexpectans, is derived from the meaning of "Sidney's surprise".[6]
144 specimens of Sidneyia are known from the Greater Phyllopod bed, where they comprise 0.27% of the community.[7]
Sidneyia sinica was named in 2002 from a specimen found in the Chengjiang Biota of South China.[8] However, it has since been rejected from the genus, and other indeterminate specimens assigned to the genus from the Spence Shale and Sirius Passet lack key diagnostic characters. Specimens that can confidently assigned to the genus include Sidneyia cf. inexpectans, known from the Wuliuan Mantou Formation of North China,[9]Sidneyia minor from the Early Cambrian (Cambrian Stage 3) Xiaoshiba Biota of Yunnan, China,[2] and a valid species of Sidneyia from Chengjiang, Sidneyia malongensis.[3]
In 1923, Sidneyia, was placed, along with Emeraldella, as part of the group "Xenopoda". Today, both Sidneyia and Emeraldella are placed as part of the clade Vicissicaudata within Artiopoda, which includes trilobites and other arthropods with similar bodyforms. However, Sidneyia and Emeraldella are usually not recovered as each others closest relatives within Vicissicaudata, rendering "Xenopoda" invalid.[10]
^ abcdeZacaï, Axelle; Vannier, Jean; Lerosey-Aubril, Rudy (2016). "Reconstructing the diet of a 505-million-year-old arthropod: Sidneyia inexpectans from the Burgess Shale fauna". Arthropod Structure & Development. 45 (2): 200–220. doi:10.1016/j.asd.2015.09.003. PMID 26410799. S2CID 12638165.
^ abcdeDu, Kunsheng; Bruton, David L.; Yang, Jie; Zhang, Xiguang (2023-02-13). "An early Cambrian Sidneyia (Arthropoda) resolves the century-long debate of its head organization". Science China Earth Sciences. 66 (3): 521–527. Bibcode:2023ScChD..66..521D. doi:10.1007/s11430-022-1019-8. ISSN 1869-1897. S2CID 257177978.
^ abcZhu, Y.; Zeng, H.; Liu, Y.; Zhao, F. (2023). "New artiopodan euarthropods from the Chengjiang fauna (Cambrian, Stage 3) at Malong, Yunnan, China". Acta Palaeontologica Polonica. doi:10.4202/app.01080.2023.
^Bicknell, Russell D.C; Paterson, John R; Caron, Jean-Bernard; Skovsted, Christian B (2017). "The gnathobasic spine microstructure of recent and Silurian chelicerates and the Cambrian artiopodan Sidneyia : Functional and evolutionary implications". Arthropod Structure & Development. 47 (1): 12–24. doi:10.1016/j.asd.2017.12.001. PMID 29221679. S2CID 46830374.
^Bicknell, Russell D. C.; Ledogar, Justin A.; Wroe, Stephen; Gutzler, Benjamin C.; Watson, Winsor H.; Paterson, John R. (2018-10-24). "Computational biomechanical analyses demonstrate similar shell-crushing abilities in modern and ancient arthropods". Proceedings of the Royal Society B: Biological Sciences. 285 (1889): 20181935. doi:10.1098/rspb.2018.1935. ISSN 0962-8452. PMC6234888. PMID 30355715.
^"The arthropod Sidneyia inexpectans , Middle Cambrian, Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society of London. B, Biological Sciences. 295 (1079): 619–653. 1981-12-18. Bibcode:1981RSPTB.295..619B. doi:10.1098/rstb.1981.0164. ISSN 0080-4622.
^Caron, Jean-Bernard; Jackson, Donald A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS. 21 (5): 451–65. Bibcode:2006Palai..21..451C. doi:10.2110/palo.2003.P05-070R. JSTOR 20173022. S2CID 53646959.
^Zhang, Xingliang; Han, Jian; Shu, Degan (27 Nov 2008). "New occurrence of the Burgess Shale arthropod Sidneyia in the Early Cambrian Chengjiang Lagerstätte (South China), and revision of the arthropod Urokodia". Alcheringa: An Australasian Journal of Palaeontology. 26: 1–8. doi:10.1080/03115510208619239. S2CID 129442308.
^Briggs, Derek E. G.; Siveter, David J.; Siveter, Derek J.; Sutton, Mark D.; Legg, David; Lamsdell, James C. (August 2023). "A vicissicaudatan arthropod from the Silurian Herefordshire Lagerstätte, UK". Royal Society Open Science. 10 (8): 230661. doi:10.1098/rsos.230661. ISSN 2054-5703. PMC10394423. PMID 37538743.
External linksedit
. Burgess Shale Fossil Gallery. Virtual Museum of Canada. 2011. Archived from the original on 2020-11-12. Retrieved 2023-02-09.
sidneyia, extinct, arthropod, known, from, fossils, found, from, early, cambrian, china, cambrian, burgess, shale, british, columbia, canada, temporal, range, cambrian, stage, wuliuan, preꞒ, reconstruction, minor, fossil, inexpectans, scientific, classificatio. Sidneyia is an extinct arthropod known from fossils found from the Early to the Mid Cambrian of China and the Mid Cambrian Burgess Shale of British Columbia Canada SidneyiaTemporal range Cambrian Stage 3 Wuliuan PreꞒ Ꞓ O S D C P T J K Pg N Reconstruction of Sidneyia minor Fossil of S inexpectans Scientific classification Domain Eukaryota Kingdom Animalia Phylum Arthropoda unranked Artiopoda unranked Vicissicaudata Genus SidneyiaWalcott 1911 Type species Sidneyia inexpectansWalcott 1911 Species S inexpectans Walcott 1911 S minor Du et al 2023 S malongensis Zhu et al 2023 Contents 1 Description 2 Ecology 3 Taxonomy 4 See also 5 References 6 External links 7 Further readingDescription edit nbsp Size comparison of Sidneyia species nbsp Biramous limb of Sidneyia inexpectans Key gnathobasic basipod pink labelled pr exopod yellow labelled ex endopod orange with terminal podomere labelled pd7 in yellow Sidneyia inexpectans reached lengths of at least 160 millimetres 6 3 in 1 The largest known specimen of S minor is around 23 mm 0 91 in long and 14 mm 0 55 in wide 2 while the largest specimen of S malongensis is 31 mm 1 2 in long and 21 mm 0 83 in wide 3 The head shield is short with notches present on the sides to accommodate stalked eyes with the underside having a hypostome The head has a pair of segmented antennae as well as three pairs of post antenal appendages This was followed by a thorax which had eight to ten segments tergites each associated with a pair of biramous appendages this was followed with one to three abdomen segments tergites with the body terminating with a telson which comprised a pair of tail flukes 2 3 The appendages bear heavily sclerotised spined basal segments basipods called gnathobases used to process food 2 1 4 In S minor the biramous appendages have 8 podomeres segments on the endopod with the last segment being a terminal claw The exopod of these limbs is flattened and bears lamellae 2 In S inexpectans the endopods of the biramous limbs have seven podomeres with the first four of these each bearing a number of thin inward projecting spines while the outer three podomeres bore more stout claw like spines with the fourth to ninth pairs of post antennal limbs bearing exopods with blade like lamellae which are thought to have been used as gills 1 S inexpectans had three pairs of digestive glands within the head shield and front of the thorax adjacent to the central gut tube 1 Ecology editSidneyia is thought to have been seafloor dwelling epibenthic generalist durophagous predator and or scavenger that used its gnathobases which closely resemble those of horseshoe crabs to crush and shred prey items including hard shelled organisms like juvenile trilobites which are abundantly preserved as stomach contents in S inexpectans and brachiopods representing around 6 of the stomach contents of S inexpectans but possibly also softer animals like worms or soft bodied arthropods like bradoriids 1 5 Taxonomy editSidneyia was discovered in 1910 during the first day of Charles Walcott s exploration of the Burgess Shale He named it after his elder son Sidney who had helped to locate the site and collect the specimen The species name Sidneyia inexpectans is derived from the meaning of Sidney s surprise 6 144 specimens of Sidneyia are known from the Greater Phyllopod bed where they comprise 0 27 of the community 7 Sidneyia sinica was named in 2002 from a specimen found in the Chengjiang Biota of South China 8 However it has since been rejected from the genus and other indeterminate specimens assigned to the genus from the Spence Shale and Sirius Passet lack key diagnostic characters Specimens that can confidently assigned to the genus include Sidneyia cf inexpectans known from the Wuliuan Mantou Formation of North China 9 Sidneyia minor from the Early Cambrian Cambrian Stage 3 Xiaoshiba Biota of Yunnan China 2 and a valid species of Sidneyia from Chengjiang Sidneyia malongensis 3 In 1923 Sidneyia was placed along with Emeraldella as part of the group Xenopoda Today both Sidneyia and Emeraldella are placed as part of the clade Vicissicaudata within Artiopoda which includes trilobites and other arthropods with similar bodyforms However Sidneyia and Emeraldella are usually not recovered as each others closest relatives within Vicissicaudata rendering Xenopoda invalid 10 See also editPaleobiota of the Burgess ShaleReferences edit a b c d e Zacai Axelle Vannier Jean Lerosey Aubril Rudy 2016 Reconstructing the diet of a 505 million year old arthropod Sidneyia inexpectans from the Burgess Shale fauna Arthropod Structure amp Development 45 2 200 220 doi 10 1016 j asd 2015 09 003 PMID 26410799 S2CID 12638165 a b c d e Du Kunsheng Bruton David L Yang Jie Zhang Xiguang 2023 02 13 An early Cambrian Sidneyia Arthropoda resolves the century long debate of its head organization Science China Earth Sciences 66 3 521 527 Bibcode 2023ScChD 66 521D doi 10 1007 s11430 022 1019 8 ISSN 1869 1897 S2CID 257177978 a b c Zhu Y Zeng H Liu Y Zhao F 2023 New artiopodan euarthropods from the Chengjiang fauna Cambrian Stage 3 at Malong Yunnan China Acta Palaeontologica Polonica doi 10 4202 app 01080 2023 Bicknell Russell D C Paterson John R Caron Jean Bernard Skovsted Christian B 2017 The gnathobasic spine microstructure of recent and Silurian chelicerates and the Cambrian artiopodan Sidneyia Functional and evolutionary implications Arthropod Structure amp Development 47 1 12 24 doi 10 1016 j asd 2017 12 001 PMID 29221679 S2CID 46830374 Bicknell Russell D C Ledogar Justin A Wroe Stephen Gutzler Benjamin C Watson Winsor H Paterson John R 2018 10 24 Computational biomechanical analyses demonstrate similar shell crushing abilities in modern and ancient arthropods Proceedings of the Royal Society B Biological Sciences 285 1889 20181935 doi 10 1098 rspb 2018 1935 ISSN 0962 8452 PMC 6234888 PMID 30355715 The arthropod Sidneyia inexpectans Middle Cambrian Burgess Shale British Columbia Philosophical Transactions of the Royal Society of London B Biological Sciences 295 1079 619 653 1981 12 18 Bibcode 1981RSPTB 295 619B doi 10 1098 rstb 1981 0164 ISSN 0080 4622 Caron Jean Bernard Jackson Donald A October 2006 Taphonomy of the Greater Phyllopod Bed community Burgess Shale PALAIOS 21 5 451 65 Bibcode 2006Palai 21 451C doi 10 2110 palo 2003 P05 070R JSTOR 20173022 S2CID 53646959 Zhang Xingliang Han Jian Shu Degan 27 Nov 2008 New occurrence of the Burgess Shale arthropod Sidneyia in the Early Cambrian Chengjiang Lagerstatte South China and revision of the arthropod Urokodia Alcheringa An Australasian Journal of Palaeontology 26 1 8 doi 10 1080 03115510208619239 S2CID 129442308 Sun Zhixin Zeng Han Zhao Fangchen March 2020 First occurrence of the Cambrian arthropod Sidneyia Walcott 1911 outside of Laurentia Geological Magazine 157 3 405 410 Bibcode 2020GeoM 157 405S doi 10 1017 S0016756819000864 ISSN 0016 7568 S2CID 202899205 Briggs Derek E G Siveter David J Siveter Derek J Sutton Mark D Legg David Lamsdell James C August 2023 A vicissicaudatan arthropod from the Silurian Herefordshire Lagerstatte UK Royal Society Open Science 10 8 230661 doi 10 1098 rsos 230661 ISSN 2054 5703 PMC 10394423 PMID 37538743 External links edit Sidneyia inexpectans Burgess Shale Fossil Gallery Virtual Museum of Canada 2011 Archived from the original on 2020 11 12 Retrieved 2023 02 09 Further reading editD L Bruton 1981 The arthropod Sidneyia inexpectans Middle Cambrian Burgess Shale British Columbia Philosophical Transactions of the Royal Society B Biological Sciences 295 1079 619 653 Bibcode 1981RSPTB 295 619B doi 10 1098 rstb 1981 0164 Retrieved from https en wikipedia org w index php title Sidneyia amp oldid 1187484302, wikipedia, wiki, book, books, library,
