Willwerathia
It is sometimes classified as synziphosurine,[1][2] a paraphyletic group of horseshoe crab-like fossil chelicerate arthropods,[2] while some studies compare its morphology to an artiopod.[1] Prosoma of Willwerathia covered by a vaulted carapace with pointed genal spines, recurved (M-shaped) ophthalmic ridges and pairs of dorsal nodes.[1] The opisthosoma of Willwerathia most likely compose of 10 segments, each expressed by a tergite that bore a median dorsal spine and a pair of tergopleurae (lateral extensions).[1] In the redescription done by Anderson et al. 1998, Willwerathia had been grouped under the synziphosurine family Weinberginidae alongside Weinbergina and Legrandella,[1] a classification which is not supported by phylogenetic analysis.[2] Willwerathia was regarded as part of the monophyletic Xiphosura sensu stricto (true horseshoe crab) by Lamsdell 2013,[2][7] but further phylogenetic analysis repeatedly resolving it within a clade compose of Bunodids, Pseudoniscids and Dekatriatan (chasmataspidids, eurypterids and arachnids).
PreꞒScientific classificationAnimaliaArthropodaChelicerataXiphosuraarthropodsynziphosurineparaphyletichorseshoe crabfossilchelicerateartiopodspeciesdepositsDevonianperiodKlerf FormationRhenish Slate MountainsGermanysynziphosurinescarapaceProsomaTergitesopisthosomatelsonpredatorLegrandellaestuarinedeltaiceurypteridJaekelopterusFalcatamacarisfamilyWeinberginidaeWeinberginaphylogeneticmonophyleticBunodidsPseudoniscidsDekatriatanchasmataspididsarachnidsSilurianMaldybulakiaCambrianNatural History Museum BernBibcodeWikidataPaleobiology Database