Dekatriata

Dekatriata is a clade of planatergan chelicerates including the groups Arachnida, Chasmataspidida, Eurypterida^[1] and additionally two stem-genera Winneshiekia and Houia.^[2] Dekatriata is defined by an opisthosoma with 13 segments as groundplan (the number proposed to be secondarily reduced in most arachnid orders^[1]) and fused, plate-like appendages on the first opisthosomal segment (somite VII).^[1]

Dekatriata Temporal range: Ordovician–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Eurypterus remipes, a eurypterid
Araneus diadematus, an arachnid
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Clade:	Planaterga
Clade:	Dekatriata Lamsdell, 2013
Groups
†Houia †Winneshiekia †Chasmataspidida Sclerophorata Arachnida †Eurypterida

References

1. Lamsdell, James C. (2012-12-18). "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.
2. Lamsdell, James; Briggs, Derek E. G.; Liu, Huaibao P.; 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. Bibcode:2015SciNa.102...63L. doi:10.1007/s00114-015-1312-5. PMID 26391849. S2CID 8153035.