New material of Adelphailurus kansensis sheds light on the cranial anatomy of an early-diverging machairodontine felid

Adelphailurus kansensis is a puma-sized felid, originally described from fragmentary material in the Edson Quarry (Kansas, Mio-Pliocene). Here, we describe a nearly complete cranium from the Wikieup local fauna of the Big Sandy Formation, along with associated dental remains, and refer it to A. kansensis. Comparative analysis with Metailurus major, Yoshi minor, Y. garevskii, and Y. yongdengensis reveals a unique combination of features. A. kansensis shares certain traits with Metailurus (narrow snout, M1 orientation) and Yoshi (rounded cranial profile) but differs from both in having thinner zygomatic arches of nearly constant width, a more pronounced postglenoid process, and specific dental characteristics, including a P3 lacking an anterior accessory cusp and upper canines with serrations on both margins. Geometric morphometric analyses place A. kansensis morphologically between Metailurus and Yoshi, illustrating its intermediate cranial proportions yet confirming its distinctiveness. Several elements, including this cranium and previously misattributed specimens, were originally referred to Pseudaelurus, highlighting the persistent taxonomic issues surrounding early diverging felids. This study refines the diagnosis of A. kansensis, and clarifies its relationships within “metailurins.”