Researhers have sequenced the genomes of two living and three extinct rhinoceros species and compared them to existing data from the remaining three living species and a range of outgroups. A paleoartist’s reconstruction of the three extinct species whose genomes were sequenced by Liu et al.: in the foreground is a Siberian unicorn (Elasmotherium sibiricum), and close behind are two Merck’s rhinoceroses (Stephanorhinus kirchbergensis); in the...