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User:Hiroizmeh/sandbox/Lobopodia

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Timeline of lobopodian research

20th century

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1910s

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1911

  • Aysheaia is described by Walcott, 1911; also naming the monotypic family Aysheaiidae, and interpreting it as a stem-polychaete [1]
  • Canadia sparsa is described by Walcott, 1911, later to be reinterpeted as Hallucigenia[1]

1920s

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1923

  • Brues, 1923 notes a resemblance between Aysheaia and Onychophora in a general study of the latter[2]

1927

  • Xenusion is decsribed by Pompeckj, 1927, interpreting it as either a worm or rangeomorph[3]

1930s

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1930

1938

  • "Lobopodia" is informally named by Snodgrass, 1938, as a group containing forms like Aysheaia and Xenusion[4]

1950s

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1958

  • Tiegs & Manton, 1958 propose a connection between Aysheaia and Tardigrada in a general study[5]

1970s

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1975

  • Delle Cave & Simonetta, 1975 interpret Aysheaia as either a stem-onychophoran or tardigrade[6]

1977

  • Hallucigenia is described by Conway Morris, 1977, although its validity is subsequently disputed[7]

1978

  • Whittington, 1978 redescribes Aysheaia and interprets it as a stem-tardigrade or onychophoran, also noting a possible relationship with Xenusion[8]

1980s

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1985

  • Robison, 1985 places Protonychophora (and Aysheaia) within Onychophora
  • Dzik & Krumbiegel, 1985 interpret Xenusion as a stem-panarthropod, naming the family Xenusiidae for Xenusion and the class Xenusia for it and Aysheaiidae

1986

  • Microdictyon is described by Bengtson, Matthews & Missarzhevsky, 1986; and placed in stem-Onychophora
  • Quadratapora is described by Bengtson, Matthews & Missarzhevsky, 1986

1987

1989

  • Hou & Chen, 1989, describe Luolishania as a stem-panarthropod near Aysheaia

1990s

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1991

  • Cardiodictyon is described by Xianguang, Ramskoeld, & Bergstroem, 1991
  • Ramskoeld & Xian-Guang, 1991, reinterpret Hallucigenia and Microdictyon as lobopodians


Consensus of studies 2017-2021 ([1]Aria & Caron 2020; [2]Edgecomb et al. 2020; [3]Aria & Caron 2017, [4]Vinther & Young 2017)

Palaeoscolecida

Taxonomy

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Lobopodia Snodgrass, 1938

  • Xenusia <Dzik & Krumbiegel, 1989 - polyphyletic class, presently disused
  • Protonychophora Hutchinson, 1930 - polyphyletic order, presently disused
  • Archonychophora Hou & Bergstrom, 1995 - polyphyletic order, presently disused
  • Paronychophora Hou & Bergstrom, 1995 - monotypic order, not consistently used
  • Scleronychophora - wastebin order, presently disused

Literature on lobopodians

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Lobopodian phylogenetic analysis character list

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Head

  1. Head length ±2x segment lengths: (0,1)
  2. Bulbous head: (0,1)
  3. Head dorsal sclerites: (0,1)
  4. Eyes: (0,1)
  5. Stalked eyes: (0,1)
  6. Oral proboscis: (0,1)
  7. Pharyngeal teeth: (0,1)
  8. Protocerebral, preocular appendages (~antennae?): (0,1)
  9. Thinner anterior legs: (0,1)
  10. Oral 'antennules'; very thin first few legs: (0,1)
  11. Number of oral antennules: (1,2, 3, 4, ...) ORD
  12. Raised 1st legs: (0,1)
  13. First leg inner spikes/bristles: (0,1)
  14. Grasper leg orientation (downward, inward): (0,1) *For primitive dinocaridids primarily
  1. Anneloid segmentation: (0,1)
  2. 'Heteronomous somitization', certain segments larger than others in a pattern: (0,1)
  3. Fleshy bristles: (0,1)
  4. Any scleritization: (0,1)
  5. Large flat sclerites: (0,1)
  6. Scleritic papillae: (0,1)
  7. Small sclerites/rough spines/barbs/spicules: (0,1)
  8. Developed, larger spikes: (0,1)
  9. Curved spikes: (0,1)
  10. Spiral spines: (0,1)
  11. Spine orientation (one row per somite, multiple rows per somite): (0,1)
  12. Pairs of Sclerites per row: (1,2,3,4,5,6) ORD
  13. Gills: (0,1)
  14. Fins/flaps: (0,1)
  15. Gut diverticulae: (0,1)
  16. Oblique muscles between outer longitudinal and inner circular muscles: (0,1)
  1. Legs: (0,1)
  2. Pairs of legs: (...,7,8,9,...) ORD
  3. Legs length +- 2x width: (0,1)
  4. Leg spacing +- 0.5x leg width: (0,1)
  5. Anterior leg length differentiation: (0,1)
  6. Rearmost legs fused at base: (0,1)
  7. Flipper-like terminal structures: (0,1)
  8. Anterior Leg setae: (0,1)
  9. Claws: (0,1)
  10. Claw number: (1,2,3) ORD
  11. 'Interconic' onychophoran-like claw structure: (0,1)

Note:*Character states 0 and 1 represent 'no' and 'yes' for their respective character unless otherwise noted

Analysis matrix

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xread
41
&[num]
Ancestral: -000000000-00- -0000000000-0000 0-0-00000-0
Antennacanthopodia: 000100-100---- --0100010001500-- 1911-0000--
Aysheaia: 000000-000-11- 1101
  1. ^ a b WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5): 109-145.
  2. ^ a b * BRUES, C. T. 1923. The geographical distribution of the Onychophora. American Naturalist, 57: 210-217.
    • WALTON, L. B. 1927. The polychaete ancestry of the insects. American Naturalist, 61: 226-250.
    • HUTCHINSON, G. E. 1930. Restudy of some Burgess Shale fossils. Proceedings of the United States National Museum, 78(11): 59.
    • WALCOTT, C. D. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections, 85(3): 1-46.
  3. ^ Dzik, J.; Krumbiegel, G. N. (1989). "The oldest 'onychophoran' Xenusion: A link connecting phyla?". Lethaia. 22 (2): 169. doi:10.1111/j.1502-3931.1989.tb01679.x.
  4. ^ Snodgrass, R.E. (1938). "Evolution of the Annelida, Onychophora, and Arthropoda". Smithsonian Miscellaneous Collections. 97 (6): 1–159.
  5. ^ Tiegs, O. W.; Manton, S. M. (1958). "The Evolution of the Arthropoda". Biological Reviews. 33 (3): 255. doi:10.1111/j.1469-185X.1958.tb01258.x. S2CID 84284702.
  6. ^ DELLE CAVE, L. AND A. M. SIMONETTA. 1975. Notes on the morphology and taxonomic position of Aysheaia (Onycophora?) and of Skania (undetermined phylum). Monitore Zoologico Italiano, 9: 67-81.
  7. ^ Conway Morris, S. (1977). "A new metazoan from the Cambrian Burgess Shale of British Columbia" (PDF). Palaeontology. 20: 623–640. Retrieved 27 January 2021.
  8. ^ Whittington, H. B. (16 November 1978). "The Lobopod animal Aysheaia pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 284 (1000): 165–197. Bibcode:1978RSPTB.284..165W. doi:10.1098/rstb.1978.0061. JSTOR 2418243.
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