Sunday, September 23, 2012


Don't you just love convergent evolution? Today's animal is a great example of the phenomenon-- it looked and acted a lot like a Hippopotamus, but was actually an ancient Rhinoceros! (Hippos and Rhinos are not closely related in any way).

This the Metamynodon, a large aquatic mammal that lived between 35 and 30 million years ago, from the Late Eocene to the early Oligocene. There are actually three different identified species (Metamynodon is the genus name), and the fossils have been uncovered in North America.

Metamynodon had a very large, round body and short legs like a Hippo does. They had eyes that were situated further up on the head, so that they could see while partially submerged. They also did not have the horns that make Rhinos so identifiable. But! Metamynodon's successor in the family tree did have the start of a horn, which, combined with the foot type (Rhinos are Perissodactyls, Hippos are not) tells us that these were not Hippos at all, just another example of Convergent Evolution.

Status : Extinct for around 30 million years
Location : North America
Size : Length up to 13ft (4m)
Classification : Phylum : Chordata -- Class : Mammalia -- Order : Perissodactyla
Family : †Amynodontidae -- Genus : †Metamynodon

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