Cheloniellida

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Cheloniellida
Temporal range: Upper Ordovician–Early Devonian
Restoration of Cheloniellon
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
(unranked): †Artiopoda
(unranked): †
Vicissicaudata
(unranked): †Cheloniellida
Broili, 1932
Genera

Cheloniellida is a taxon (usually referred to as an order

Vicissicaudata within Artiopoda.[3][4][5]

Morphology

Ventral structures of the anterior region of Cheloniellon calmani, showing differentiation between appendages.

The flattened, ovoid body of cheloniellid comprises an

tergites (dorsal exoskeleton). The cephalon could be divided into procephalon and gnathocephalon.[2] Compared to other members of Artiopoda, the head shield (dorsal exoskeleton of cephalon) of cheloniellid is relatively reduced.[2][3] The trunk is wider than the cephalon and is made up of 8-13 tergites.[2] The pleural (lateral) tips of first few tergites are directed anterolaterally, becoming increasingly posterolaterally directed rearward, giving the segmental boundaries between tergites a radiated appearance.[3][2] The last trunk segment, also known as postabdomen,[4] is tiny and laterally encompassed by the pleural regions of previous tergite.[2]

Based on available materials, the cephalon comprises a pair of antennae and 5 pairs of uniramus appendages, with the posterior 4 pairs bore gnathobases.[6] There are evidences that the non-gnathobasic second cephalic appendages are specialized or even raptorial in some species.[6][2] Each of the trunk segments (except the last one) has a pair of biramous appendages each consisting of a leg-like endopod and a shorter exopod.[2] The last trunk segment has a pair of spine/whip-like appendages referred as furcae[3] or cerci,[6] some species bore a medial spine between it which may or may not be a telson.[2]

Classification

Phylogenetic position

chelicerate prosomal appendages by some studies.[6][7]

While Boudreaux (1979) regarded Cheloniellida as a class,

neuroanatomical[20][21] and developmental[22]
evidences (suggests that chelicerae are in fact deutocerebral).

Artiopoda
Summarized phylogeny of Artiopoda with focus on Cheloniellida, based on Lerosey-Aubril et al. (2017).[4]

As of 21st century, Cheloniellida was mostly found to form a clade with

chelicerates
.

Included genera and species

The unambiguous members of cheloniellids shown as follows:

  • Cheloniellon Broili, 1932
    • Cheloniellon calmani Broili, 1932—Lower Devonian, Germany
  • Duslia Jahn, 1893
    • Duslia insignis Jahn, 1893—Upper Ordovician, Czech Republic, Morocco
  • Eoduslia Van Roy, 2006 (unpublished?)
    • Eoduslia brahimtahiri Van Roy, 2006—Upper Ordovician, Morocco (unpublished?)
  • Neostrabops Caster & Macke, 1952
    • Neostrabops martini Caster & Macke, 1952—Upper Ordovician, United States
  • Paraduslia Dunlop, 2002
    • Paraduslia talimaae Dunlop, 2002—Lower Devonian, Russia
  • Pseudarthron Selden & White, 1984
    • Pseudarthron whittingtoni Selden & White, 1984—Upper Silurian
  • Triopus Barrande, 1872
    • Triopus drabowiensis Barrande, 1872—Upper Ordovician, Czech Republic, Morocco

In 2018, a new species (informally named "

Latromirus" in an unpublished thesis from 2016[27]) was described in a preprint by Wendruff et al.[2] According to Braddy & Dunlop 2021, the enigmatic Parioscorpio may have cheloniellid affinities,[28] however that interpretation is denied by Van Roy et al. 2022, only remaining specimen UWGM 2439 (holotype specimen of "Latromirus") as possible cheloniellid.[29]

References

  1. ^
    OCLC 38305908
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  2. ^ a b c d e f g h i j k l m n Wendruff, Andrew James, et al. "New cheloniellid arthropod with large raptorial appendages from the Silurian of Wisconsin, USA." BioRxiv (2018): 407379. [1]
  3. ^
    S2CID 85744103
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  4. ^
    PMID 28894246
    .
  5. S2CID 89985331
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  6. ^
    S2CID 87725308
    .
  7. ^ a b c STfJRMER, W. t~ BERGSTROM, J. 1981. Weinbergina, a xiphosuran arthropod from the Devonian Hunsriick Slate. - Palaontologische Zeitschrift 55: 237-255.[2] Archived 2020-06-20 at the Wayback Machine
  8. ^ Boudreaux H. B., 1979. Significance of intersegmental tendon system in arthropod phylogeny and monophyletic classification of Arthropoda. pp. 551-586. In.: Gupta A.P. [Ed.]. Arthropod Phylogeny. Van Nostrand Reinhold Company, N.Y., 1-762
  9. ^ Chlupác I. The enigmatic arthropod Duslia from the Ordovician of Czechoslovakia. Palaeontol. 1988; 31:611–620.[3]
  10. ^ BROILI, F. (1932): Ein neuer Crustacee aus dem rheinischen Unterdevon. -- Sitzungsber. bayer. Akad. Wiss.: 27--38; Miinchen.[4]
  11. ^ BROILI, F. (1933): Ein zweites Exemplar von Cheloniellon. -- Sitzungsber. bayer. Akad. Wiss.: 11--32; Miinchen.[5]
  12. ^ Delle Cave, L. and A.M. Simonetta (1991) Early Palaeozoic arthropods and problems of arthropod phylogeny; with some notes on taxa of doubtful affinities. In The Early Evolution of Metazoa and the Significance of Problematic Taxa, eds. A. M. Simonetta and S. Conway Morris. Cambridge University Press, Cambridge, England. Vol. 189–244.
  13. ^ Wills, M. A., Briggs, D. E. G., Fortey, R. A. & Wilkinson, M. 1995. The significance of fossils in understanding arthropod evolution. Verhandlungen der deutschen zoologischen Gesselschaft 88, 203–15.
  14. ISBN 978-94-011-4904-4
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  16. PMID 11874919
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  17. S2CID 4307398
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  18. S2CID 833103
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  19. S2CID 6048195
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  20. S2CID 13101102
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  21. ISSN 1467-8039
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  22. S2CID 13101102
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  23. ISSN 0567-7920
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  24. ^
    S2CID 15290784
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  25. ^
    S2CID 133058010
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  26. PMID 24077329
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  27. ^ Wendruff, Andrew J. (2016). Paleobiology and Taphonomy of Exceptionally Preserved Organisms from the Brandon Bridge Formation (Silurian), Wisconsin, USA (Thesis). The Ohio State University.
  28. S2CID 245285654
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  29. S2CID 249652930
    .
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