Chasmataspis
Temporal range: Early Ordovician
Holotype specimen
Life reconstruction of C. laurencii
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Clade: Dekatriata
Order: †Chasmataspidida
Family: †Chasmataspididae
Caster & Brooks, 1956
Genus: †Chasmataspis
Caster & Brooks, 1956
Type species
†Chasmataspis laurencii
Caster & Brooks, 1999

Chasmataspis is a genus of chasmataspidid, a group of extinct aquatic chelicerate arthropods.[1][2] It was found in the Early Ordovician deposits of Tennessee, United States.[3]

Morphology

Just like other chasmataspidids, the body of Chasmataspis compose of a prosoma and a 13-segmented opisthosoma, with the latter subdivided into a 4-segmented preabdomen and a 9-segmented postabdomen.[4] Dorsal to the carapace were pairs of ridges, lateral eyes and median ocelli.[4] Chasmataspis characterized by a semicircular carapace (prosomal dorsal shield) with pointed genal spines and preabdomen with fused body segments.[4] Rows of tubercles and spines run through the axial and lateral regions of opisthosoma.[4] The body terminated with a spine-like telson.[4]

There is no body fossils of Chasmataspis with unambiguous appendages being discovered.[4] The only evidence were 2 specimens of disarticulated, claw-bearing appendages discovered from the same stratum which may represent the prosomal appendage (possibly appendage VI[3]) of Chasmastaspis.[4]

References

  1. ↑ Dunlop, Penney & Jekel 2020, p. 16.
  2. ↑ Caster & Brooks 1956.
  3. 1 2 Lamsdell, James C.; Gunderson, Gerald O.; Meyer, Ronald C. (2019-01-08). "A common arthropod from the Late Ordovician Big Hill Lagerstätte (Michigan) reveals an unexpected ecological diversity within Chasmataspidida". BMC Evolutionary Biology. 19 (1): 8. doi:10.1186/s12862-018-1329-4. ISSN 1471-2148. PMC 6325806. PMID 30621579.
  4. 1 2 3 4 5 6 7 Dunlop, Jason A.; Anderson, Lyall I.; Braddy, Simon J. (2003). "A redescription of Chasmataspis laurencii Caster & Brooks, 1956 (Chelicerata: Chasmataspidida) from the Middle Ordovician of Tennessee, USA, with remarks on chasmataspid phylogeny" (PDF). Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 94 (3): 207–225. doi:10.1017/S0263593300000626. ISSN 1473-7116.

Cited bibliography


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