Buzz
Many are aware that whales are mammals, but how does this relate to the 'grand family' mostly residing on land?
Take a closer look at a whale - the largest creatures on Earth. It's challenging to imagine their connection to the mammalian family on land. However, scientists have uncovered a surprising link to a species that few would have guessed, allowing them to sketch out a 'phylogenetic tree' for this unique marine mammal.
Specifically, the closest 'siblings' on land to whales are hippos. Based on fossil records, researchers discovered that the ancestors of whales were land-dwelling mammals around 47-52 million years ago.
The ancestors of whales at that time gradually adapted to a semi-aquatic life along the coast. They utilized the aquatic environment to escape predators and find additional food. This transition occurred gradually, and they eventually 'moved' entirely to the world of marine royalty, settling down for the long haul.
The direct ancestors of whales back then didn't resemble their oceanic descendants much. This species was called Pakicetus, living entirely on land but with swimming abilities comparable to today's dogs or bears.
The ancestors of whales appear more like an exaggerated rodent with a long snout than the majestic oceanic titans they are known as today.
But what do the ancestors of whales have to do with a hooved, semi-aquatic creature like the hippopotamus? Since the late 18th century, scientists have been curious about the similarities in the reproductive organs of these two 'cousins,' initially dismissing it as mere coincidence.
It wasn't until nearly 200 years later, around the 1980s, when the Pakicetus fossilized skeleton was unearthed, revealing bone features found only in whales (Cetacea) and even-toed ungulates (Artiodactyla), including camels, giraffes, pigs, and, of course, hippos.
The Pakicetus skeleton.
Specifically, the ear bones of Pakicetus contain two distinctive features found only in these two orders, providing whales with the ability to hear underwater. Their limb bones are also unique, with a pair of hooks only present in even-toed ungulates, not in odd-toed ones like horses or rhinos.
Modern science further contributes to unraveling many related questions. DNA studies of whales and even-toed ungulates show similarities in gene segments. Moreover, whales possess a gene segment found exclusively in one other species - none other than the hippopotamus.
According to scientists, the evolution from Pakicetus to the entirely different form of modern whales took place predominantly within a miraculous 10 million years - a marvel in the animal kingdom. Additionally, uncovering the connection between whales and hippos or even-toed ungulates provides us with insights into their past and enhances awareness for future conservation efforts.
Source: ROM
