The Origin(s) of Whales

Ambulocetidae is treated in the synthesis as a sampled Eocene fossil family with amphibious anatomical interpretations; those specimens test locomotor transitions but do not form a demonstrated linear ancestor series.

Basilosauridae is synthesized as a sampled late Eocene radiation of fully aquatic archaeocetes with several distinct genera; the family grouping does not imply that every basilosaurid lies on the direct ancestry of Neoceti.

A systematic synthesis recognizes Cetacea from a sequence of separately sampled Eocene fossils and living lineages, but explicitly combines paleontological, anatomical, stratigraphic and molecular evidence rather than documenting one continuous population or exact origination event.

Cetaceamorpha is used here as a navigation route joining raoellid evidence to sampled Cetacea; Uhen’s synthesis reviews those relationships but does not present the route as one observed lineage, a direct ancestor chain or a dated crown group.

Mysticeti is treated as the baleen-whale branch of sampled Neoceti, with toothed stem forms and later baleen-bearing lineages documenting a mosaic rather than an instantaneous transformation or one direct ancestor.

Neoceti is used for the sampled crown-whale branch joining Mysticeti and Odontoceti in the synthesis; the Eocene–Oligocene timing discussed there combines fossil and model evidence and is not a direct observation of the crown split.

Odontoceti is treated as the toothed-whale branch of sampled Neoceti, but its early fossil membership and character sequence are reconstructed from separate taxa; the branch is not a single observed lineage or an exact 34 Ma origin event.

Pakicetidae is reviewed as a separately sampled early Eocene cetacean family represented by incomplete and composite material; its placement helps test early whale relationships but does not make the family a direct ancestral stage for all later whales.

The synthesis recognizes Protocetidae as a diverse, geographically dispersed assemblage of middle Eocene whales with varying amphibious adaptations; it is not reduced to one ancestor, habitat or uninterrupted global range.

The whale-origin synthesis treats sampled raoellids as close fossil relatives used to test the land-to-water transition, while their relationship to Cetacea remains a phylogenetic inference rather than evidence that a raoellid specimen was a direct whale ancestor.

Cetacea is displayed at 53–0 Ma only as a review-bounded fossil-to-living navigation envelope, not an exact cetacean origination date. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

Basilosauridae is displayed at 41–34 Ma only as the review's sampled late-Eocene radiation, not exact family FAD/LAD. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

cetaceamorpha is displayed at 53–0 Ma only as an editorial navigation envelope across separately sampled fossils and living whales, not one observed lineage or origin date. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

raoellidae is displayed at 48–47 Ma only as the sampled raoellid interval in the whale-origin review, not a direct whale ancestor or global family range. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

pakicetidae is displayed at 50–47 Ma only as the review's sampled pakicetid interval, not a linear ancestral stage or exact endpoints. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

ambulocetidae is displayed at 48–47 Ma only as the review's sampled ambulocetid interval, not a linear ancestral stage or exact endpoints. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

protocetidae is displayed at 47–37.7 Ma only as the review's diverse protocetid sample, not uninterrupted global occupancy or exact endpoints. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

neoceti is displayed at 36–0 Ma only as a synthesis-bounded crown-whale navigation envelope, not a directly observed crown split. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

mysticeti is displayed at 34–0 Ma only as the review's sampled stem-to-living mysticete envelope, not an exact clade origin. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

odontoceti is displayed at 34–0 Ma only as the review's sampled stem-to-living odontocete envelope, not an exact clade origin. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.