Threatened arthropods United States, and IUCN Red List for international purposes. Only a tiny fraction of the planet's endangered arthropods are formally recognized as such, as no one has ever evaluated the conservation status of the vast majority of arthropod species. It is difficult to estimate the total number of endangered arthropod species, since many of the taxa themselves have not been recorded. For example, in North America the estimated number of insect species exceeds 163,000, of which only about two thirds are taxonomically known. An even greater discovery awaiting, over 72 percent of North American arachnids are yet to be named
Diania as the armoured Lobopodia. These have long been assumed to be related in some way to Arthropoda and it seems likely that arthropods evolved from somewhere within this group. However, all previously discovered lobopodians showed soft, rather ring-like, but not segmented legs. The significance of "Diania" is that it is a lobopodian which appears to have evolved the name-giving character of the arthropods: jointed legs. In the original description of the fossil the authors suggested that "Diania" could be the sister group of "Schinderhannes" and the remaining arthropods, but discussed the possibility that it may be a more primitive form