Eldonia

Eldonia; Temporal range: Cambrian Stage 3–Middle Ordovician PreꞒ Ꞓ O S D C P T J K Pg N
	Eldonia ludwigii from the middle Cambrian Burgess Shale.
	Life restoration
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Stem group:	Ambulacraria
Clade:	†Cambroernida
Class:	†Eldonioidea
Family:	†Eldoniidae
Genus:	†Eldonia; Walcott 1911
Type species
	E. ludwigi; Walcott 1911
Species
	E. ludwigi Walcott 1911; E. eumorpha Sun & Hou 1987; E. berbera Alessandrello 2003;
Synonyms
	†Yunnanomedusa Sun & Hou 1987; ? †Stellostomites Sun & Hou 1987;

Eldonia is an extinct soft-bodied^[3] cambroernid^[4] best known from the Fossil Ridge outcrops of the Burgess Shale, particularly in the 'Great Eldonia layer' in the Walcott Quarry.^[5] In addition to over 550 specimens collected by Walcott,^[6] 224 specimens of Eldonia are known from the Greater Phyllopod bed, where they comprise 0.43% of the community.^{[citation needed]} Species also occur in the Chengjiang biota,^[7] Siberia,^[8] and in Upper Ordovician strata of Morocco.^[9]

Description

It takes the form of a round, medusoid disk (which originally led to suggestions of a jellyfish affinity)^[7] with a C-shaped gut trace. The gut is recalcitrant and can be extracted using Hydrofluoric acid.^[10]

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.^[11]

Classification

Walcott's original interpretation as a holothurian was rapidly disputed.^[12] Alternative affinities to be suggested, which did not stand the test of time, included the siphonophores^[13]^[14]^[15] and a coelenterate medusa.^[16]

Eldonia and the other Eldoniidae form a clade, Eldonioidea, with the Rotadiscidae and the informal group known as the paropsonemids.^[1] The Eldonioidea are, in turn, part of the stem-ambulacrarian clade Cambroernida.^[4]

There are three species within Eldonia,^[1] although some authors consider E. eumorpha to be a distinct genus, Stellostomites, as S. eumorphus.^[17]

Paleoecology

The organism is frequently found in association with the lobopod Microdictyon, which is presumed to have fed on Eldonia.^[18]

Eldonia berbera
Eldonia ludwigii, Walcott Quarry. About 4 cm long

References

^ ^a ^b ^c Schroeder, Paterson & Brock 2018, p. 80–81
^ Chen, Zhu & Zhou 1995, pp. 240–241
^ Chen, Zhu & Zhou 1995, p. 214
^ ^a ^b Li et al. 2023, pp. 2362–2364
^ Gabbott, Zalasiewicz & Collins 2008, p. 311, 316–317
^ Durham 1974, p. 752
^ ^a ^b Chen, Zhu & Zhou 1995, p. 213
^ Friend, Zhuravlev & Solov’ev 2002, p. 463
^ Alessandrello & Bracchi 2003
^ Butterfield 1990
^ Fang et al. 2022, p. 5
^ Clark 1912, pp. 276–278
^ Madsen 1957, p. 281
^ Madsen 1962
^ Madsen 1956
^ Henning 1960
^ Caron et al. 2010
^ Zhang & Hou 2007, pp. 448–449

Works cited

Alessandrello, Anna; Bracchi, Giacomo (2003). "Eldonia berbera n. sp., a new species of the enigmatic genus Eldonia Walcott, 1911 from the Rawtheyan (Upper Ordovician) of little Atlas (Erfoud, Tafilalt, Morocco)" (PDF). Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale in Milano. 144 (2). Milano: 337–358. ISSN 0037-8844.
Butterfield, N. J. (1 July 1990). "Organic Preservation of Non-Mineralizing Organisms and the Taphonomy of the Burgess Shale". Paleobiology. 16 (3): 247–399. Bibcode:1990Pbio...16..272B. doi:10.1017/s0094837300009994. ISSN 0094-8373. JSTOR 2400788. S2CID 133486523.
Caron, J.; Conway Morris, S.; Shu, D.; Soares, D. (2010). Soares, Daphne (ed.). "Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes". PLOS ONE. 5 (3): e9586. Bibcode:2010PLoSO...5.9586C. doi:10.1371/journal.pone.0009586. PMC 2833208. PMID 20221405.
Chen, Jun-yuan; Zhu, Mao-yan; Zhou, Gui-qing (1995). "The early Cambrian medusiform metazoan Eldonia from the Chengjiang Lagerstätte" (PDF). Acta Palaeontologica Polonica. 40 (3): 213–244.
Clark, H. L. (1912). "Fossil Holothurians". Science. 35 (894): 274–278. JSTOR 1638409. PMID 17809248. Retrieved 28 December 2024.
Durham, J. W. (1974). "Systematic Position of Eldonia ludwigi Walcott". Journal of Paleontology. 48 (4): 750–755. Bibcode:1974JPal...48..524M. JSTOR 1303225.
Fang, Xiang; Mao, Yingyan; Liu, Qi; Yuan, Wenwei; Chen, Zhongyang; Wu, Rongchang; Li, Lixia; Zhang, Yuchen; Ma, Junye; Wang, Wenhui; Zhan, Renbin; Peng, Shanchi; Zhang, Yuandong; Huang, Diying (2022). "The Liexi fauna: a new Lagerstätte from the Lower Ordovician of South China". Proceedings of the Royal Society B. 289 (1978): 1—8. doi:10.1098/rspb.2022.1027. PMC 9277276. Retrieved 28 December 2024.
Friend, D.; Zhuravlev, A. Yu.; Solov’ev, I. A. (2002). "Middle Cambrian Eldonia from the Siberian Platform". Paleontological Journal. 36 (1): 20–24. Retrieved 28 December 2024.
Gabbott, S. E.; Zalasiewicz, J.; Collins, D. (2008). "Sedimentation of the Phyllopod Bed within the Cambrian Burgess Shale Formation of British Columbia". Journal of the Geological Society. 165 (1): 307–318. Bibcode:2008JGSoc.165..307G. doi:10.1144/0016-76492007-023. S2CID 128685811.
Henning, Lemche (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.
Li, Yujing; Dunn, Frances S.; Murdock, Duncan J.E.; Guo, Jin; Rahman, Imran A.; Cong, Peiyun (May 10, 2023). "Cambrian stem-group ambulacrarians and the nature of the ancestral deuterostome". Current Biology. doi:10.1016/j.cub.2023.04.048. Retrieved 11 May 2023.
Madsen, F. J. (1956). "Eldonia, a Cambrian Siphonophore-formerly interpreted as a Holoturian[sic]". Videnskabelige Meddelelser Fra Dansk Naturhistorisk Forening I Københaven. 118: 7–14.
Madsen, F. J. (1957). "On Walcott's Supposed Cambrian Holothurians". Journal of Paleontology. 31 (1): 281–282. Bibcode:1974JPal...48..524M. JSTOR 1300523.
Madsen, F. J. (1962). "The systematic position of the Middle Cambrian fossil Eldonia" (PDF). Medd. Dan. Geol. Foren. 15: 87–89.
Schroeder, Natalie I.; Paterson, John R.; Brock, Glenn A. (2018). "Eldonioids with associated trace fossils from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia". Journal of Paleontology. 92 (1): 80–86. Bibcode:2018JPal...92...80S. doi:10.1017/jpa.2018.6. ISSN 0022-3360. S2CID 197586878.
Signor, P. W.; Vermeij, G. J. (1 July 1994). "The Plankton and the Benthos: Origins and Early History of an Evolving Relationship". Paleobiology. 20 (3): 259–406. Bibcode:1994Pbio...20..297S. doi:10.1017/s0094837300012793. ISSN 0094-8373. JSTOR 2401005. S2CID 87094600.
Zhang, X-G; Hou, X-G (Dec 2007). "Gravitational Constraints on the Burial of Chengjiang Fossils". Palaios. 22 (6): 513–518. Bibcode:2007Palai..22..448Z. doi:10.2110/palo.2006.p06-085r. ISSN 0172-4622. S2CID 128830203. Retrieved 28 December 2024.

External links

"Eldonia ludwigi". Burgess Shale Fossil Gallery. Virtual Museum of Canada. 2011. Archived from the original on 2020-11-12.

[Schroeder2018-1] Schroeder, Paterson & Brock 2018, p. 80–81

[2] Chen, Zhu & Zhou 1995, pp. 240–241

[soft-3] Chen, Zhu & Zhou 1995, p. 214

[Li2023-4] Li et al. 2023, pp. 2362–2364

[Gabbott2008-5] Gabbott, Zalasiewicz & Collins 2008, p. 311, 316–317

[6] Durham 1974, p. 752

[Chen1995-7] Chen, Zhu & Zhou 1995, p. 213

[8] Friend, Zhuravlev & Solov’ev 2002, p. 463

[9] Alessandrello & Bracchi 2003

[Butterfield1990-10] Butterfield 1990

[Fang2022-11] Fang et al. 2022, p. 5

[12] Clark 1912, pp. 276–278

[13] Madsen 1957, p. 281

[14] Madsen 1962

[15] Madsen 1956

[16] Henning 1960

[Caron2010-17] Caron et al. 2010

[Zhang2007-18] Zhang & Hou 2007, pp. 448–449

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