English: Horseshoe crabs.
Synonym: Merostomata.
Clades:
Chelicerata;
Arthropoda;
Animals.
IntroductionXiphosurales is a Order in
Chelicerata.
Xiphosura have hardly changed in hundreds of millions of years and are considered living fossils.
TaxonomyXiphosura were traditionally placed in the class Merostomata, including Eurypterida. Merostomata turned out to be paraphyletic. Now Eurypterida is classified within Sclerophorata together with the arachnids, and therefore, Merostomata is now a synonym of
Xiphosura.
FamilesXiphosurida
Limulidae