A peer-reviewed analysis of 26 adult Uintatherium skulls found little consistent support for the extreme sex differences long attributed to this extinct horned mammal. The same methods distinguished sex differences more clearly in bison. Modest variation in canines and horns remains possible, while fossil damage and uncertain identification of individual sex constrain the comparison.
Uintatherium anceps, an extinct mammal with three pairs of skull projections and long upper canines, has long been depicted with much larger, more prominently horned males. A single peer-reviewed fossil study published on 7 October found little consistent support for that extreme contrast. Kevin Mulcahy compared linear measurements from 26 complete or partial adult skulls, using permanent teeth to identify mature animals.[1]
The fossils come from the Bridger and Washakie basins in southwestern Wyoming. The statistical comparisons considered horns, canine teeth and the length of the skull. The same analyses, applied to a similarly sized bison sample, revealed clearer sex differences. Uintatherium results leave room for more modest variation in canines and horns.[1]
Some broken skull regions had been restored with plaster, leaving uncertainty about where original bone ends and restoration begins. A fossil rarely allows direct identification of the animal’s sex, while age and individual variation can also affect dimensions. The analyses using multiple variables omitted the most fragmented skulls. The small sample limits interpretation, and the study calls for a larger fossil collection and additional analyses of skull shape rather than concluding that the sexes were identical.[1]
