Saurischia is represented by the sampled early-dinosaur matrix that places Tawa within Saurischia; the result is a phylogenetic hypothesis and does not make Tawa a direct ancestor or establish an exact clade range.
claim:taxon:saurischiaAtlas home / References / A Complete Skeleton of a Late Triassic Saurischian and the Early Evolution of Dinosaurs
References / paperA Complete Skeleton of a Late Triassic Saurischian and the Early Evolution of Dinosaurs
Nesbitt, S.J.; Smith, N.D.; Irmis, R.B.; Turner, A.H.; Downs, A.; Norell, M.A.
Year2009
Source roleprimary-study
DOI / ID10.1126/science.1180350
Fitness and scope
taxonomy · topology · range · morphology · methods
Primary description of Tawa plus a sampled early-dinosaur phylogenetic analysis; placement is not evidence of direct ancestry or a clade-wide first appearance.
Claim ledger
Saurischia is displayed at 215–213 Ma only as the dated Late Triassic Tawa-bearing interval used in the sampled saurischian analysis, not a Saurischia origin date. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.
claim:taxon:saurischia:source-bounded-range-rc49