In the brain of a sabertooth: First neuroanatomical description and ethological insights on Megantereon cultridens (Felidae, Machairodontinae).

We present the first detailed neuroanatomical study of Megantereon cultridens, a key member of the sabertoothed tribe Smilodontini, based on digital endocasts obtained via computed tomography of three fossil skulls from Spain, Italy, and France. Through qualitative anatomical description, regional brain volume estimation, and 3D geometric morphometrics, we assess the neuroanatomy of this extinct felid in comparison with extant pantherine and feline species. In comparison to modern felids, the endocranial morphology of M. cultridens reveals a rostrocaudally compressed cerebrum, a relatively enlarged frontal lobe, short olfactory tracts, and a diverging sulcal pattern, particularly in the configuration of the sulcus ectosylvius. While the absence of a distinct gyrus intersylvius suggests a reduced auditory cortex, the expanded occipital cortex may indicate enhanced visual processing. The expanded cerebellum indicates a preference for closed environments and scansorial abilities for this genus. Finally, all performed analyses place M. cultridens in an intermediate position between Felinae and Pantherinae in brain shape morphospace, with closest affinities to ecologically flexible extant species such as Puma concolor and Panthera onca. Our findings support the hypothesis that M. cultridens possessed a generalized neuroanatomical profile, likely associated with behavioral plasticity and ecological versatility in the Early Pleistocene European ecosystems characterized by a high degree of intraguild competition and an especially high diversity of medium to large felids.