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Chasmataspidida was named by Caster and Brooks (1956). It was considered monophyletic by Dunlop et al. (2003).

It was reranked as the suborder Chasmataspidina by Bergström (1968).

It was assigned to Synziphosurida by Bergström (1968); to Xiphosura by Bergström (1975); to Merostomata by Sepkoski (2002); to Euchelicerata by Dunlop et al. (2003); to Dekatriata by Lamsdell (2013); and to Planaterga by Dunlop et al. (2020).

Synonymy list
YearName and author
1956Chasmataspidida Caster and Brooks
1968Chasmataspidina Bergström p. 502
1975Chasmataspidida Bergström p. 304
1978Diploaspidida Simonetta and Delle Cave
2002Chasmataspidida Sepkoski
2003Chasmataspidida Dunlop et al. p. 222
2013Chasmataspidida Lamsdell p. 20
2020Chasmataspidida Dunlop et al. p. 7

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EubilateriaAx 1987
phylumArthropodaLatreille 1829
subphylumChelicerataHeymons 1901
EuchelicerataWeygoldt and Paulus 1979
orderChasmataspididaCaster and Brooks 1956
orderChasmataspididaCaster and Brooks 1956

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Or. †Chasmataspidida Caster and Brooks 1956
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Fm. †Chasmataspididae Caster and Brooks 1956
G. †Chasmataspis Caster and Brooks 1956
Chasmataspis laurencii Caster and Brooks 1956
Fm. †Diploaspididae Stormer 1972
G. †Achanarraspis Anderson et al. 2000
Achanarraspis reedi Anderson et al. 2000
G. †Diploaspis Størmer 1972
Diploaspis casteri Størmer 1972
Diploaspis muelleri Poschmann et al. 2005
G. †Dvulikiaspis Marshall et al. 2014
Dvulikiaspis menneri Novojilov 1958
G. †Forfarella Dunlop et al. 1999
Forfarella mitchelli Dunlop et al. 1999
G. †Heteroaspis Størmer 1972
Heteroaspis stoermeri Novojilov 1959
Invalid names: Heteroaspis novojilovi Størmer 1972 [synonym]
G. †Loganamaraspis Tetlie and Braddy 2004
G. †Nahlyostaspis Marshall et al. 2014
Nahlyostaspis bergstroemi Marshall et al. 2014
G. †Octoberaspis Dunlop 2002
Octoberaspis ushakovi Dunlop 2002
G. †Skrytyaspis Marshall et al. 2014
Skrytyaspis andersoni Marshall et al. 2014
G. †Kiaeria Stoermer 1934
Kiaeria limuloides Størmer 1934
Invalid names: Chasmataspidacea Caster and Brooks 1956 [empty], Diploaspidida Simonetta and Delle Cave 1978 [synonym], Heteroaspididae Størmer 1972 [empty]
No diagnoses are available
No measurements are available
Locomotion: actively mobilep
Created: 2004-02-29 09:38:49
Modified: 2004-02-29 11:38:49
Source: p = phylum
Reference: Kiessling 2004

Age range: base of the Llanvirn to the top of the Pragian or 468.00000 to 407.60000 Ma

Collections (7 total)

Time interval Ma Country or state Original ID and collection number
Llanvirn468.0 - 458.4USA (Tennessee) Chasmataspis laurencii (37450)
Rootsikula426.2 - 422.9Norway Kiaeria limuloides (14308)
Lochkovian419.2 - 410.8Russian Federation (Siberia) Heteroaspis stoermeri, Dvulikiaspis menneri (60391)
Lochkovian419.2 - 410.8Russian Federation (Krasnoyarsk Krai) Dvulikiaspis menneri, Skrytyaspis andersoni (231624)
Lochkovian419.2 - 410.8Russian Federation Heteroaspis stoermeri, Skrytyaspis andersoni (26989)
Pragian410.8 - 407.6Germany Diploaspis muelleri (152107)
Early/Lower Emsian409.1 - 402.5Germany (Alken) Diploaspis casteri, Heteroaspis novojilovi (27049)