Superregnum: Eukaryota
Cladus: Amorphea
Cladus: Obazoa
Cladus: Opisthokonta
Cladus: Holozoa
Cladus: Filozoa
Cladus: Choanozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: ParaHoxozoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Superphylum: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Chelicerata
Classis: Merostomata
Ordo: †
Subordines: †Eurypterina – †Stylonurina
Ichnogenera: †Palmichnium

Eurypterida Huxley, 1857: 133

• Gigantostraca Haeckel, 1866: xc
• Cyrtoctenida Størmer & Waterston, 1968

• Haeckel, E. 1866. Generelle Morphologie der Organismen. Allgemeine Grundzüge der organischen Formen-Wissenschaft, mechanisch begründet durch die von Charles Darwin reformirte Descendenztheorie. Zweiter Band: Allgemeine Entwickelungsgeschichte der Organismen. clx + 462 pp., pls I–VIII. Berlin: Georg Reimer. BHL Reference page. 
• Huxley, T.H. 1857. Lectures on general natural history, lecture X. Medical Times and Gazette (n.s.) 14 (= 35): 133–135, 181–183, 255–257, 353–355. HathiTrust 👁 Open access
  .
• Størmer, L. & Waterston, C.D. 1968. Cyrtoctenus gen. nov., a large late Palaeozoic arthropod with pectinate appendages. Transactions of the Royal Society of Edinburgh 68(4): 63–104. DOI: 10.1017/S0080456800014563 👁 Paywall
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• Lamsdell, J.C. 2025. Codex Eurypterida: A Revised Taxonomy Based on Concordant Parsimony and Bayesian Phylogenetic Analyses. Bulletin of the American Museum of Natural History 473: 1–196. DOI: 10.1206/0003-0090.473.1.1 👁 Open access
  . Reference page. 
• Størmer, L. 1955. Merostomata. In: Moore, R.C. (ed.): Treatise on Inver­tebrate Paleontology, P, Arthropoda 2, P4–P41. Geological Society of America and University of Kansas Press, Lawrence, Kansas. DOI: 10.17161/dt.v0i0.5345 👁 Open access
  . [as subclass]