Xiphodon

Xiphodon (from Ancient Greek ξίφος (xíphos), meaning "sword", and ὀδούς (odoús), meaning "tooth") is the type genus of the extinct Palaeogene artiodactyl family Xiphodontidae. It, like other xiphodonts, was endemic to Western Europe and lived from the Middle Eocene up to the earliest Oligocene. Fossils from Montmartre in Paris, France that belonged to X. gracilis were first described by the French naturalist Georges Cuvier in 1804. Although he assigned the species to Anoplotherium, he recognized that it differed from A. commune by its dentition and limb bones, later moving it to its own subgenus in 1822. Xiphodon was promoted to genus rank by other naturalists in later decades. It is today defined by the type species X. gracilis and two other species, X. castrensis and X. intermedium.

Xiphodon had specialized bladelike selenodont dentition, with its brachyodont (low-crowned) incisors, canines, and premolars having sharp edges for cutting through higher vegetation such as leaves and shrubs. It also retained primitive molars compared to its relative Dichodon, indicating different dietary specializations. Xiphodon is also the only xiphodontid to be known from postcranial fossils. Its skull morphology, combined with slender and elongated limbs, suggest similar behaviours to North American Palaeogene camelids such as Poebrotherium, including cursoriality (running adaptations). However, the full extent of its behaviour and evolutionary relationships remain uncertain, and its resemblances to camelids are probably an instance of convergent evolution.