Waeringopteridae

s of Waeringopterus. Although waeringopterid fossils remain rare and in most cases fragmentary and very little concrete information on the group can confidently be established due to the poor fossil record, Like all other chelicerates, and other arthropods in general, waeringopterid eurypterids possessed segmented bodies and jointed appendages (limbs) covered in a cuticle composed of proteins and chitin. The chelicerate body is divided into two tagmata (sections); the frontal prosoma (head) and posterior opisthosoma (abdomen). In the waeringopterids, the fifth pair of appendages were spiniferous. The telson (the posteriormost segment of the body) was xiphous (long and pointed). The eyes of waeringopterid eurypterids were located close to the marginal rim of the carapace (the "head" plate). == Classification ==

The Waeringopteridae is the only family within the superfamily Waeringopteroidea and contains the genera Eysyslopterus, Grossopterus, Orcanopterus and Waeringopterus. This analysis recovered Eysyslopterus as an adelophthalmoid. "Waeringopteridae" and the superfamily that includes it, "Waeringopteroidea" (named after eurypterid researcher Erik N. Kjellesvig-Waering), were not formally published clades until 2025. The names originally derived from a 2004 thesis by O. Erik Tetlie and were as such not actually technically valid names until a later paper formalised them. Nevertheless, as phylogenetic analyses confirmed the grouping as monophyletic and the names supply an easy way to refer to the group, they remained routinely used within studies centered around eurypterid taxonomy. In these studies, the names are usually within quotation marks and/or are noted to not be properly valid names that derive from a thesis. The group was also sometimes referred to as the "waeringopteroid clade" rather than as the "Waeringopteroidea" within studies to differentiate it from the properly described superfamilies, before the formal publication of Waeringopteroidea. In addition to Grossopterus, Orcanopterus, and Waeringopterus, Lamsdell also recovered Eysyslopterus as inside Waeringopteridae: == Distribution and paleobiogeography ==

Out of the known waeringopterid species, most are from the fossil deposits in areas that were part of the ancient continent of Laurentia. Only Grossopterus overathi, from the Devonian of Germany, == See also ==