Whale Ancestors

Where did whales come from? How did a fish evolve to become as large as a modern whale?

Actually, whales took a round-about route to evolve into today’s huge ocean creatures. They are actually descended from a land animal.

There are plenty of clues in a whale’s body and biology that their ancestors lived on land:

* They breathe air.

* They nurse their young with their own milk.

* Their paddle-shaped flippers encase hand bones with five ‘fingers’.

* As embryos, whales have tiny back limbs which disappear before birth.

It turns out that hippos are the closest living relatives of whales, but not their ancestors. Both hippos and whales evolved from four-legged, even-toed, hoofed ancestors that lived on land about 50 million years ago. The hippo’s ancestor stayed on land, but the whale ancestor—which was about the size of a goat—moved to the sea and evolved into swimming creatures over a period of about 8 million years, which is quite fast for evolutionary processes.

When fossils of gigantic ancient whales were first discovered, they were mistaken for dinosaur fossils and given the name Basilosaurus. But later, they were recognized as mammals. These prehistoric whales were more elongated than modern whales and had small back legs and front flippers. Their nostrils were situated halfway between the tip of the snout and the forehead. They had earbones just like those of modern whales. Therefore, Basilosaurus showed the link between whales and their terrestrial ancestor.

The current theory is this: That some land-living hoofed animals favoured the flavor of plants at the water’s edge. Eating them had the added advantage of allowing them to easily hide from danger in shallow water. Over time, their descendants spent more and more time in the water, possibly in an ancient estuary, and their bodies became adapted for swimming. The front legs became flippers. A thick layer of fat called blubber replaced their fur coats to keep them warm and streamlined. Their tails became bigger and stronger for powerful swimming, and their back legs shrunk. Their nostrils gradually moved to the top of their heads so that they could breathe easily without having to tilt their heads while swimming. As these creatures began to feed on a different diet, they lost their teeth in favor of a baleen filter method of feeding.

Between these articles, there was some disagreement about what whale ancestors ate. One stated that they favored plants found at the water’s edge. Another felt they ate small land animals and fish found close to shore. Neither article had any information on the teeth whale ancestors had, so their eating preferences seem pretty much up in the air.

So, what can we learn from this tale of whales? Be careful what and where you eat? Evolution is your friend? I find myself wondering if whales would ever come back out of the water, what would they evolve to then? Some version of a goat-sized, hoofed animal again? One of the articles did mention that occasionally, a whale comes along that does have vestigial back legs that are completely encased within their body. Therefore, it seems possible that back legs could make a comeback.

Come on, work with me here. If octopuses can come out of the ocean and become a terrestial bad guy, as some scientists seem to think, then surely whales can also emerge from the oceans. Given enough time to evolve.

 

https://us.whales.org/whales-dolphins/how-did-whales-evolve/

https://evolution.berkeley.edu/evolibrary/article/evograms_03

https://www.nhm.ac.uk/discover/when-whales-walked-on-four-legs.html