World Hippo Day on February 15 celebrates the extraordinary hippopotamus and encourages people to take action to prevent its extinction. Did you know that before 1909, scientists placed hippos in the same group as pigs? Despite their outward similarities with pigs or wild boars, hippopotamuses are closely related to whales, dolphins, and porpoises. Hippos are semiaquatic mammals that are native to sub-Saharan Africa. They are herbivores and can weigh up to 2,000kg, making them the third-largest land mammal after elephants and rhinos. Hippos are primarily found in rivers, lakes, and mangrove swamps.
HISTORY OF WORLD HIPPO DAY
Hippos are thought to have originated from a group of semiaquatic animals called Whippomorpha. This group later split into two branches around 54 million years ago. The first branch, which includes whales and dolphins, evolved to become complete aquatic cetaceans. The second branch became anthracotheres, a close ancestor of the common hippo.
During the Pliocene Epoch (over two million years ago), all branches of the anthracotheres went extinct, except those that evolved into Hipopotamidae. This group of hippo ancestors migrated to Africa around 35 million years ago and dominated the continent as one of the earliest large mammals. Between 16 and eight million years ago, the oldest known hippopotamid, Kenyapotamus, strived in the African continent. But the group that later evolved into the modern hippo was Archaeopotamus, which lived between 7.5 and 1.8 million years ago in Africa and the Middle East.
There were ancestors of the hippo in Europe and the British Isles before the last glaciation, including the European hippopotamus — Hippopotamus antiquus — Hippopotamus major, and Hippopotamus gorgops. But these species of hippos went extinct, and the exact reason is still unknown, although scientists hypothesize it might be because of man.
Ancestors of European hippos migrated to many Mediterranean islands during the Pleistocene, evolved, and later became extinct. These species of hippos include Cyprus dwarf hippopotamus, Hippopotamus pentlandi, Hippopotamus melitensis, and Hippopotamus creutzburgi. Between 50,000 and 16,000 years ago, all hippos in the supercontinent, Eurasia, went extinct.
In North America, there were anthracothere genera in the early Oligocene (over 23 million years ago), but no evidence of hippos has ever been found on the continent. Many attempts have been made to introduce the species into the U.S., but they have never been successful. That was until Pablo Escobar illegally imported four hippos to Columbia in the late 1980s. This population of hippos has since grown to about 100.
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