Compare one frog genome, receptor-knockout metamorphosis and a synthetic species timetree without treating extant datasets as fossils, ancestors or complete taxonomic coverage.
Each step names its evidence claims, with references below. Interactive Explorer states are available in the full application; the narrative remains an editorial synthesis.
The Xenopus tropicalis draft assembly is a powerful extant reference with an accession and known sampling boundary, not a genome for all amphibians.
Extant genomic comparison does not directly observe lineage origins.
claim:event:xenopus-tropicalis-draft-genomeTRβ knockout delays tail regression while TRα knockout advances hindlimbs, making the experiment mechanistic but model- and tissue-specific.
Experimental causation in one laboratory model is not a universal amphibian rule.
claim:event:xenopus-thyroid-receptor-metamorphosisThe 7,238-species posterior uses molecular data for 4,061 species and soft taxonomic inference for the rest; its times are model outputs.
COL26.8 naming coverage, sequence sampling and mature evidence dossiers remain different inventories.
claim:event:extant-amphibian-7238-species-timetree