Eldonia Explained

Eldonia is an extinct soft-bodied cambroernid animal of unknown affinity,[1] best known from the Fossil Ridge outcrops of the Burgess Shale, particularly in the 'Great Eldonia layer' in the Walcott Quarry.[2] In addition to the 550 collected by Walcott,[3] 224 specimens of Eldonia are known from the Greater Phyllopod bed, where they comprise 0.43% of the community.[4] Species also occur in the Chengjiang biota,[5] Siberia,[6] and in Upper Ordovician strata of Morocco.

A specimen from the Lower Ordovician Madaoyu Formation in Hunan, South China, can be interpreted as the incomplete body of Eldonia or the similar animal. However, its annulation, the structure of the intestine and the shape of the body are more similar to those of Ottoia.[7]

Description

It takes the form of a round, medusoid disk (which originally led to suggestions of a jellyfish affinity) with a C-shaped gut trace. The gut is recalcitrant and can be extracted using Hydrofluoric acid.[8]

Classification

Walcott's original interpretation as a holothurian was rapidly disputed.[9] Alternative affinities to be suggested, which did not stand the test of time, included the siphonophores[10] [11] [12] and a coelenterate medusa.[13]

The eldoniids form a clade that also includes Paropsonema, Rotadiscus, and Stellostomites.[14]

Paleoecology

The organism is frequently found in association with the lobopod Microdictyon, which is presumed to have fed on Eldonia.[15]

See also

External links

Notes and References

  1. P. W. . G. J.. Vermeij. 1 July 1994 . The Plankton and the Benthos: Origins and Early History of an Evolving Relationship. Signor. Paleobiology. 20. 3. 259–406. 0094-8373. 2401005. 10.1017/s0094837300012793 . 1994Pbio...20..297S. 87094600.
  2. S. E.. J.. D. . Sedimentation of the Phyllopod Bed within the Cambrian Burgess Shale Formation of British Columbia. Gabbott . Journal of the Geological Society . 165 . 1. 307–318 . 2008 . 10.1144/0016-76492007-023. Zalasiewicz. Collins . 2008JGSoc.165..307G. 128685811.
  3. 1303225. 750–755. Systematic Position of Eldonia ludwigi Walcott. Journal of Paleontology. 48. 4. 1974 . Durham. J. W.. 1974JPal...48..524M.
  4. Caron . Jean-Bernard. Jackson . Donald A.. Taphonomy of the Greater Phyllopod Bed community, Burgess Shale. PALAIOS . 21 . 5 . 451–65. October 2006. 10.2110/palo.2003.P05-070R. 20173022. 2006Palai..21..451C . 53646959 .
  5. M-Y. ZHU. G. Q. ZHOU. 1995 . The early Cambrian medusiform metazoan Eldonia from the Chengjiang Lagerstätte.. Acta Palaeontologica Polonica. 213–244. CHEN, J-Y.. 40.
  6. D. Friend . A. Yu. Zhuravlev . I. A. Solov’ev . amp . 2002 . Middle Cambrian Eldonia from the Siberian Platform . dead . Paleontological Journal . 36 . 1 . 20–24 . https://web.archive.org/web/20160303191129/http://www.maik.ru/abstract/paleng/2/paleng1_2p20abs.htm . 2016-03-03.
  7. Xiang Fang, Yingyan Mao, Qi Liu, Wenwei Yuan, Zhongyang Chen, Rongchang Wu, Lixia Li, Yuchen Zhang, Junye Ma, Wenhui Wang, Renbin Zhan, Shanchi Peng, Yuandong Zhang, Diying Huang. 2022. The Liexi fauna: a new Lagerstätte from the Lower Ordovician of South China. Proceedings of the Royal Society B. 289. 1978. 1—8. 10.1098/rspb.2022.1027. en. 9277276.
  8. N. J.. Organic Preservation of Non-Mineralizing Organisms and the Taphonomy of the Burgess Shale. Paleobiology. 16. 3. Butterfield. 247–399. 1 July 1990 . 0094-8373. 10.1017/s0094837300009994 . 2400788. 1990Pbio...16..272B. 133486523.
  9. 10.1126/science.35.894.274-a. 1638409. 274–278. Fossil Holothurians. Science. 35. 894. 1912 . H. L.. 17809248. Clark.
  10. 1300523. 281–282. On Walcott's Supposed Cambrian Holothurians. Journal of Paleontology. 31. 1. 1957 . F. J. . Madsen. 1974JPal...48..524M.
  11. The systematic position of the Middle Cambrian fossil Eldonia. MADSEN, F. J.. 1962 . Medd. Dan. Geol. Foren. 15. 87–89.
  12. MADSEN, F. J.. 1956 . Videnskabelige Meddelelser Fra Dansk Naturhistorisk Forening I Københaven. 7–14. Eldonia, a Cambrian Siphonophore-formerly interpreted as a Holoturian[sic].. 118.
  13. Lemche, Henning. 1960. A possible central place for Stenethecoides Resser, 1939 and Cambridium Horny, 1957 (Mollusca Monoplacophora) in invertebrate phylogeny. . Rep. Int. Geol. Congr.. XXI Session, Norden . Pt. 22. 92–101.
  14. 5. Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes . D.. 3. e9586. PLOS ONE. 2833208. 10.1371/journal.pone.0009586. Soares. Caron. 2010. 20221405 . D. . J.. Conway Morris. Shu . S.. Soares. Daphne. 2010PLoSO...5.9586C . free .
  15. Zhang . X-G. Hou . X-G . Gravitational Constraints on the Burial of Chengjiang Fossils. PALAIOS. 22. 6. 513–518. Dec 2007 . 0172-4622. 10.2110/palo.2006.p06-085r . 2007Palai..22..448Z. 128830203. Submitted manuscript.

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