Chasmataspidida information

Chasmataspidida; Temporal range: Ordovician–Mid Devonian PreꞒ Ꞓ O S D C P T J K Pg N Possible Cambrian record
	Fossils of Hoplitaspis hiawathai.
	Reconstruction of Dvulikiaspis menneri (middle top), Octoberaspis ushakovi (top left), Hoplitaspis hiawathai (top right), Chasmataspis laurencii (bottom left) and Diploaspis casteri (bottom right).
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Clade:	Dekatriata
Order:	†Chasmataspidida; Caster & Brooks, 1956
Clades
	†Chasmataspididae Caster & Brooks, 1956; †Diploaspididae Størmer, 1972; †Kiaeria Størmer, 1934;
Synonyms
	Diploaspidida Simonetta & Delle Cave, 1978;

Chasmataspidids, sometime referred to as chasmataspids,^[1]^[2]^[3] are a group of extinct chelicerate arthropods that form the order Chasmataspidida. Chasmataspidids are probably related to horseshoe crabs (Xiphosura) and/or sea scorpions (Eurypterida),^[4]^[1] with more recent studies suggest that they form a clade (Dekatriata) with Eurypterida and Arachnida.^[5]^[6]^[7]^[8] Chasmataspidids are known sporadically in the fossil record through to the mid-Devonian,^[9] with possible evidence suggesting that they were also present during the late Cambrian.^[1] Chasmataspidids are most easily recognised by having an opisthosoma divided into a wide forepart (preabdomen) and a narrow hind part (postabdomen) each comprising 4 and 9 segments respectively.^[1]^[10] There is some debate about whether they form a natural (i.e. monophyletic) group.^[3]^[1]^[4]

^ ^a ^b ^c ^d ^e ^f Cite error: The named reference Chasmataspis2004 was invoked but never defined (see the help page).
^ Cite error: The named reference :0 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference :1 was invoked but never defined (see the help page).
^ ^a ^b Garwood, Russell J.; Dunlop, Jason A. (2014). "Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders". PeerJ. 2: e641. doi:10.7717/peerj.641. PMC 4232842. PMID 25405073.
^ Lamsdell, James C. (2013-01-01). "Revised systematics of Palaeozoic 'horseshoe crabs' and the myth of monophyletic Xiphosura". Zoological Journal of the Linnean Society. 167 (1): 1–27. doi:10.1111/j.1096-3642.2012.00874.x. ISSN 0024-4082.
^ Selden, Paul A.; Lamsdell, James C.; Qi, Liu (2015). "An unusual euchelicerate linking horseshoe crabs and eurypterids, from the Lower Devonian (Lochkovian) of Yunnan, China". Zoologica Scripta. 44 (6): 645–652. doi:10.1111/zsc.12124. ISSN 1463-6409. S2CID 55264483.
^ Lamsdell, James C.; Briggs, Derek E. G.; Liu, Huaibao P.; Witzke, Brian J.; McKay, Robert M. (2015). "A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids". The Science of Nature. 102 (9–10): 63. doi:10.1007/s00114-015-1312-5. ISSN 0028-1042. PMID 26391849. S2CID 8153035.
^ Lamsdell, James C. (2016). Zhang, Xi-Guang (ed.). "Horseshoe crab phylogeny and independent colonizations of fresh water: ecological invasion as a driver for morphological innovation". Palaeontology. 59 (2): 181–194. doi:10.1111/pala.12220. S2CID 85553811.
^ Cite error: The named reference :3 was invoked but never defined (see the help page).
^ Dunlop, Jason A.; Lamsdell, James C. (2017). "Segmentation and tagmosis in Chelicerata". Arthropod Structure & Development. 46 (3): 395–418. doi:10.1016/j.asd.2016.05.002. ISSN 1467-8039. PMID 27240897.

[Chasmataspis2004-1] ^ ^a ^b ^c ^d ^e ^f Cite error: The named reference Chasmataspis2004 was invoked but never defined (see the help page).

[:0-2] Cite error: The named reference :0 was invoked but never defined (see the help page).

[:1-3] Cite error: The named reference :1 was invoked but never defined (see the help page).

[Garw-4] Garwood, Russell J.; Dunlop, Jason A. (2014). "Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders". PeerJ. 2: e641. doi:10.7717/peerj.641. PMC 4232842. PMID 25405073.

[:2-5] Lamsdell, James C. (2013-01-01). "Revised systematics of Palaeozoic 'horseshoe crabs' and the myth of monophyletic Xiphosura". Zoological Journal of the Linnean Society. 167 (1): 1–27. doi:10.1111/j.1096-3642.2012.00874.x. ISSN 0024-4082.

[Houia2015-6] Selden, Paul A.; Lamsdell, James C.; Qi, Liu (2015). "An unusual euchelicerate linking horseshoe crabs and eurypterids, from the Lower Devonian (Lochkovian) of Yunnan, China". Zoologica Scripta. 44 (6): 645–652. doi:10.1111/zsc.12124. ISSN 1463-6409. S2CID 55264483.

[Winneshiekia2015-7] Lamsdell, James C.; Briggs, Derek E. G.; Liu, Huaibao P.; Witzke, Brian J.; McKay, Robert M. (2015). "A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids". The Science of Nature. 102 (9–10): 63. doi:10.1007/s00114-015-1312-5. ISSN 0028-1042. PMID 26391849. S2CID 8153035.

[HorseshoeCrabPhylo2015-8] Lamsdell, James C. (2016). Zhang, Xi-Guang (ed.). "Horseshoe crab phylogeny and independent colonizations of fresh water: ecological invasion as a driver for morphological innovation". Palaeontology. 59 (2): 181–194. doi:10.1111/pala.12220. S2CID 85553811.

[:3-9] Cite error: The named reference :3 was invoked but never defined (see the help page).

[:5-10] Dunlop, Jason A.; Lamsdell, James C. (2017). "Segmentation and tagmosis in Chelicerata". Arthropod Structure & Development. 46 (3): 395–418. doi:10.1016/j.asd.2016.05.002. ISSN 1467-8039. PMID 27240897.

Chasmataspidida information

and 30 Related for: Chasmataspidida information

Chasmataspidida

Dekatriata

Arthropod

Arachnid

Xiphosura

Chasmataspis

Chelicerata

Hoplitaspis

Tactopoda

Megarachne

Eurypterid

Offacolus

List of arthropod orders

Hibbertopterus

Onychopterellidae

Eurypterus

Jaekelopterus

Largest prehistoric animals

Pterygotus

Dvulikiaspis

Moselopterus

Echinognathus

Patrick Burn Formation

Pentlandopterus

Douglas Lake Member

Adelophthalmidae

Archopterus

Salteropterus

Pentecopterus

Forfarella

Chasmataspidida Temporal range: Ordovician–Mid Devonian PreꞒ Ꞓ O S D C P T J K Pg N Possible Cambrian record^[1]

Fossils of Hoplitaspis hiawathai.

Reconstruction of Dvulikiaspis menneri (middle top), Octoberaspis ushakovi (top left), Hoplitaspis hiawathai (top right), Chasmataspis laurencii (bottom left) and Diploaspis casteri (bottom right).
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Clade:	Dekatriata
Order:	†Chasmataspidida Caster & Brooks, 1956
Clades
†Chasmataspididae Caster & Brooks, 1956 †Diploaspididae Størmer, 1972 †Kiaeria Størmer, 1934
Synonyms
Diploaspidida Simonetta & Delle Cave, 1978