The placental mammal ancestor and the post–K–Pg radiation of placentals

CAGS 01-IG-1a,b preserves an articulated skeleton with dentition, feet and claws; the original matrix placed Eomaia near the eutherian root and inferred scansoriality, while later combined matrices can place it outside Theria, so neither topology nor locomotor habit is a directly observed ancestral state.

A matrix of 4,541 phenomic characters for 86 living and fossil species, combined with 27 nuclear genes, produced one parsimony tree with post-K–Pg crown-placental diversification and a reconstructed ancestral phenotype; both chronology and phenotype are model outputs rather than observations of an ancestor.

CAGS 01-IG-1a,b was recovered as basal Eutheria in the original matrix, while later combined analyses can move Eomaia outside Theria; neither result is ancestry.

The profile is restricted to the Yixian Formation occurrence in Liaoning and does not establish a global eutherian or therian origin area.

Dentition and limb proportions support faunivorous and scansorial interpretations, while feeding and locomotor behaviour were not directly observed.

The articulated holotype preserves skull, dentition, much of the postcranium, feet and claws used in anatomical and phylogenetic comparisons.

The 125.8–124.1 Ma envelope is the Yixian sample context, not a universal therian FAD, eutherian calibration or direct specimen date.

The 100–0 Ma Placentalia route is a model envelope: a molecular analysis estimated a roughly 103 Ma deep placental split, whereas the phenomic combined analysis placed sampled crown diversification after K–Pg; neither model is a fossil FAD or ancestor observation.

The 58.3–0 Ma Xenarthra route retains the Riostegotherium entry from a combined phenomic–molecular chronology as a sampled/model bound; it is not a securely dated global FAD, crown origin or complete fossil range.

The 66–0 Ma Glires route is a K–Pg-to-present navigation/model envelope contextualized by post-K–Pg placental analyses and a 47.8–41.2 Ma Mimolagus fossil sample; it does not date crown Glires or assert continuous fossil occupancy.