Genus-rank taxa of this atlas whose own sourced description states that their biological classification is disputed, unresolved or genuinely uncertain, so that no kingdom or class placement can be assigned with confidence. Incertae sedis is the standard taxonomic term for exactly this condition, used across paleontology and biology for a taxon of uncertain systematic position rather than a coined label. Covers mostly enigmatic Ediacaran and Cambrian fossil genera whose original describers, and often decades of subsequent study, could not settle whether the organism was an animal, a plant, a fungus, a colonial microbial structure or something outside any living kingdom, such as the disk shaped Ediacaran fossils of Aspidella, the modular chambered organism Curviacus, and the globose Cambrian structures of Erytholus whose very status as a biological fossil at all remains disputed. Also covers a handful of younger fossil genera whose classification is disputed between two entirely different groups rather than simply unknown, such as Cestites, argued to be either a ctenophore or an early land liverwort, and Rhyniognatha, argued to be either an insect or a myriapod. A genus belongs here only when its own sourced description explicitly says its affinity is uncertain, unresolved or disputed, or gives no biological classification at all beyond a vague descriptor such as problematic fossil or enigmatic organism; a genus whose description names a settled class, order or other taxonomic placement, even one reached only by resemblance to a named relative, belongs in the matching kingdom or class subcategory instead, never here by default.