If you were asked to find a whale, you’d probably look at the bottom of the ocean (or, at the very least, your nearest aquarium.) However, buried in the dry sands of Cairo, Egypt, lie the remnants of a once-thriving ocean species: a group of ancient, footed whales known as Archaeoceti.
Wadi Al-Hitan (“Valley of the Wales”) was once the floor of a vast ocean millions of years ago. Now, dunes cover several fossils of a long-lost suborder. These 50-foot long serpentine skeletons look more like the remains of eels than whales, though they are indeed related to Shamu.
If you know a little bit about evolution, you'll recognize the common pattern: stuff in the oceans grows legs, makes it to land, ends up as dinosaurs, etc, etc. This is a highly simplified version, and it doesn’t tell the whole truth. While all life on land originated in the water, some species decided to go back.
Whales, dolphins, narwhals, porpoises and many other oceanic mammals make up an evolutionary branch (or clade) known as Cetacea (from the Greek word ‘Ketos,’ meaning ‘big fish.’) Organisms in this branch all originate from a common ancestor: an ancient mammal who, after living on dry land and watching one too many episodes of ‘Mako Mermaids,’ decided to return to the water, trade their legs for fins and live the ocean life.
This whole process occurred over 50 million years ago (evolution favors those who play the waiting game.) Keep in mind that evolution isn’t a purposeful, singular movement towards one particular outcome; it’s more like throwing a plate of spaghetti at the wall and seeing what sticks. As such, after the whale’s common ancestor began to live, eat and breed in the water, having fins instead of fully developed, weight-bearing limbs was more evolutionarily advantageous.
The mammalian links between the common ancestor of today’s Cetaceans (which also gave rise to hippos) and modern-day whales are numerous.
It’s obvious that Archaeoceti were waterborne. Their long bodies made water navigation swift and efficient. Their forelimbs were paddle-like for swimming, and their hind limbs were more or less useless (which, in biology, you call ‘vestigial.’) Their spiny teeth indicate that these creatures were no peaceful herbivores, but rather carnivorous.
The fossils themselves weren’t discovered until 1902, and they weren’t excavated until 1980, when all-terrain vehicles made rough desert navigation possible. The site is currently a UNESCO World Heritage Site and also hosts fossils for ancient sea snakes, turtles, crocodiles and ancestors to the modern-day manatee. Tours are only available on a limited basis, so consider a date at the New York Museum of Natural History if you want to see evolution at work.
Next time you go whale-watching, consider this: these behemoths once walked on land. Because sometimes, when you get out of the ocean in the morning, you just want to hit the evolutionary ‘snooze’ button and go right the heck back. Stay weird this semester!