New Skull Reframes Early Saber-Toothed Cat Evolution

A nearly complete Arizona skull of Adelphailurus kansensis reveals it was a cougar-sized, early-diverging machairodontine with less exaggerated upper canines and a mosaic of features between Metailurus and Yoshi. The find clarifies its place on the saber-toothed lineage, supports the idea that longer fangs emerged and then persisted (a macroevolutionary ratchet), helps untangle its taxonomic history from Pseudaelurus, and suggests a separate primitive saber-toothed migration into North America. The study, published online June 19, 2026 in the Journal of Vertebrate Paleontology, advances understanding of the origins and diversification of saber-toothed predators.