Taking that as the metric how have the writers of the paper in the OP proved that the species that produced these bone fragments was not able to produce [fertile] offspring with any other species (of which they have a few bone fragments), or even with modern humans.<p>Even with a full genome, or a full skeleton is it even possible? Surely the only way we currently have to determine mating compatibility is to have live subjects to mate&#x2F;extract gametes from and means to incubate the zygote [and care for it to adulthood].