New findings suggest that the now enormous hippopotamus that we see came from an ancestor a twentieth of its size. This finally closes a gap in the evolutionary history of the hippopotamus.
It was believe in the past that hippopotamuses share an evolutionary ancestor with whales, but gaps in the fossil record kept scientists from making the connection. However, researchers have discovered a new species — one identified by 30 million-year-old molars found in Kenya — that reunites the modern hippo with its family tree.
Fabrice Lihoreau, a paleontologist at the University of Montpelier in France, and the lead author of the study, said. “We know quite well the story of whales, because lots of people are looking for fossils of whales, and we have a complete evolutionary history of them. But for the hippo, we only knew what was going on in the past 20 million years. Earlier than that, we couldn’t recognize anything as a hippo.”
The researchers uncovered several teeth from a new anthrocothere species at Lokone Hill, including molars and incisors. Similar to teeth in modern-day hippos, the molars showed a distinctive three-leaf pattern that looks a bit like a maple leaf. The researchers named the new species Epirigenys lokonensis, which roughly translates to ‘original hippo from Lokone’.
According to the researchers, the molar pattern revealed that E. lokonensis was a direct ancestor to hippos. Because mammal teeth are so unique, patterns on the molars can serve as a kind of species fingerprint, enabling paleontologists to tie ancient creatures to their modern descendants.
The researchers added that the E. lokonensis was probably just 220 pounds (100 kg), much smaller than the lumbering 3 ton hippos of today. But just like today’s pudgy creatures, these animals lived in the water. The findings also confirm that hippopotami first evolved in Africa and were related to whales.
“When you do a safari, you want to see a lion and you want to see an antelope, but these animals come from Asia. They are not really African mammals. But Hippo is really an African mammal,” added Lihoreau.
The findings were published in the Nature Communications journal.