The atlas separates Darriwilian total-group plates from a much younger modelled crown origin, so fossil occurrence and molecular divergence are not conflated.
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The oldest fossil material assigned to Echinoidea consists of disarticulated bothriocidaroid plates from the Pygodus serra Zone of the Darriwilian; time-scaled analyses place the bothriocidaroid root in the Dapingian or Darriwilian.
claim:taxon:echinoidea:ordovician-stem-recordPhylogenomic dating places the origin of crown Echinoidea between the Pennsylvanian and Cisuralian across analyses, with most posterior probability in the early Permian; Ordovician echinoids are stem-group records.
claim:taxon:echinoidea:crown-originOrdovician bothriocidaroids are treated as stem echinoids, whereas crown Echinoidea is defined and dated separately in the phylogenomic analysis.
claim:taxon:echinoidea:taxonomyThe highlighted Darriwilian plates are sampled occurrences and do not establish a global origin area or complete early distribution.
claim:taxon:echinoidea:biogeographyLiving Echinoidea span shallow- and deep-water, epifaunal and infaunal, omnivorous and detritivorous modes; neither the global occurrence study nor disarticulated stem plates establishes one ancestral ecology or body-size envelope.
claim:taxon:echinoidea:ecologyBothriocidaroid plates document stem-echinoid test construction, while crown-character evolution is evaluated in a separate phylogenomic framework.
claim:taxon:echinoidea:morphologyThe 460–0 Ma range uses Darriwilian total-group material; it is not the crown origin, which is modelled much later across sampled analyses.
claim:taxon:echinoidea:fossil-range