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
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Clade:	Planaterga
Clade:	Dekatriata Lamsdell, 2013
Groups
†Houia †Winneshiekia †Chasmataspidida Sclerophorata Arachnida †Eurypterida