Read one fossil organ, several clock and biogeographic models, and a living-lineage topology without turning unlike evidence into one false origin timeline.
Each step names its evidence claims, with references below. Interactive Explorer states are available in the full application; the narrative remains an editorial synthesis.
PB22285 preserves a Ginkgo-like combination of wood characters in 153–165 Ma strata, but an isolated organ cannot identify a complete plant or set the first appearance of Ginkgophyta.
A specimen occurrence, a whole-plant association and a clade first appearance are three different claims.
claim:event:tiaojishan-ginkgoxylonA plastome clock combining fossil and tectonic constraints places the living Cycadaceae crown much older than a Miocene-only story, while alternative schemes reveal wide model sensitivity.
The event dates a modelled crown of living Cycadaceae, not the fossil first appearance of all cycads.
claim:event:cycadaceae-palaeogene-crown-modelAdding fossil leaves to a species-level model expands inferred past cycad latitudes and multiplies inferred local extirpations, demonstrating that living distributions alone erase history.
The wide interval summarizes a modelled transition; it is not one precisely dated global extinction pulse.
claim:event:cycad-latitudinal-contractionThe 2011 estimate that most sampled living cycad species are no older than roughly 12 Ma remains historically important, but later fossil-integrated work prevents it from becoming the age of Cycadales.
Living-species radiation, crown age, stem history and fossil first appearance must stay separate.
claim:event:living-cycad-radiation-modelSouthern Hemisphere conifer lineages in one living-species time tree have older median nodes than sampled northern lineages, but those medians are neither family origins nor fossil ranges.
The comparison excludes Gnetales and does not validate the atlas's provisional Araucariaceae range.
claim:event:conifer-hemisphere-node-patternA broad nuclear dataset recovers cycads plus Ginkgo and a Gnetales–Pinaceae relationship among living families, while gene-tree conflict and extinct lineages remain visible limits.
This hypothesis does not replace the global navigation tree or supply chronological branch lengths.
claim:event:extant-gymnosperm-backbone