On the Tayassuid affinities of Xenohyus Ginsburg, 1980, and the description of new fossils from Spain

Abstract

In 1980, Ginsburg created the new genus Xenobyus for a large suiform artiodactyl which he considered to belong to the family Suidae. Among the distinguishing characters of the genus, Ginsburg cited the enlarged, strongly curved and inflated central upper incisors possessing a distal accessory cusplet, the shortened muzzle, the enlarged lower first and second incisors, and the c10se packing of the entire tooth row (i.e. reduced to absent diastemata). These and other characters, such as the vertically implanted mandibular canines, the sympbyseal morphology, and the shape of the third upper incisor, suggest that Xenobyus belongs instead to the family Tayassuidae, subfamily Doliochoerinae. Whereas Ginsburg suggested that Xenobyus had an unknown ancestry and that it represented an immigrant into Europe at about the beginning of zone MN2b, it now seems more likely that it represents a late doliochoere of the sort represented by Doliochoerus quercyi which occurs in late Stampian deposits (Ginsburg, 1974). In many ways it is merely an enlarged version of this species, but there are sufficient morphological differences to warrant retention of the genus Xenobyus. Viewed within a tayassuid framework, Xenobyus is not seen to be unusual and not to run counter to evolutionary trends in the Suidae, the latter view being a necessity following its identifiation as a suid. Sorne fundamental similarities between tbe molars of Xenobyus and Kenyapotamus could provide a link between late doliochoeres and early hippopotamids, an hypothesis already mentioned by Pickford (1983). Newly discovered fossils from Loranca, Cuenca, Spain belong to two different species of Xenobyus, X venitor and an undescribed larger species. Nuevos fósiles, descubiertos en Loranca (Cuenca, España), pertenecientes a dos diferentes especies de Xenobyus; X vemtor y Xenobyus sp. de talla mayor que el anterior, son también descritos en este trabajo.