Genetic analyses have tested the existence of three of these putative subspecies. Three species of Malagasy hippopotamus became extinct during the Holocene on Madagascar, one of them within the past 1,000 years.
A study examining mitochondrial DNA from skin biopsies taken from 13 sampling locations, considered genetic diversity and structure among hippo populations across the continent. The Malagasy hippos were smaller than the modern hippopotamus, likely through the process of insular dwarfism.
The hippopotamus is a highly aggressive and unpredictable animal and has attacked humans. A rough evolutionary lineage can be traced from Eocene and Oligocene species: Anthracotherium and Elomeryx to the Miocene species Merycopotamus and Libycosaurus and the very latest anthracotheres in the Pliocene.
They are threatened by habitat loss and poaching for their meat and ivory canine teeth. Hippopotamuses are gregarious, living in groups of up to thirty animals. The hippopotamus is the type genus of the family Hippopotamidae. Merycopotamus, Libycosaurus and all hippopotamids can be considered to form a clade, with Libycosaurus being more closely related to hippos.
The authors found low, but significant, genetic differentiation among H. Three species of hippopotamus, the European hippopotamus (Hippopotamus antiquus), Hippopotamus major and Hippopotamus gorgops, ranged throughout continental Europe and the British Isles.