When archaeologists excavate a monument in the desert, what do you most expect them to find? A pyramid? A cave full of treasures? Or a cemetery, in which, there are preserved mummies like this?
Certainly, even the most imaginative people have a hard time figuring it out: Beneath the desert sands there could be whales. But here, in Peru’s Ocucaje desert, scientists have found the skull of an ancient whale 36 million years old.
The fossil was identified as a primitive marine mammal. That is, it is the common ancestor of modern whales and dolphins. However, with a body length of up to 17 meters, this whale is also known as basilosaurus, meaning “lizard king”.
Paleontologists think that in the past, basilosaurus could swim in water like a sea snake. But this whale has a very large skull. Basically, it looks like a snake attached to a giant face, with sharp teeth.
With those features, this giant monster must be a carnivorous whale. They are thought to be able to knock down sharks and other ancient whales to stay at the top of the food chain.
But there is another question you are probably wondering: Why are there whale fossils in the middle of the desert?
Ancient whale fossils were found in the Ocucaje desert 350 kilometers south of the Peruvian capital Lima.
As it turns out, the site of what is now the Ocucaje desert 350 kilometers south of the Peruvian capital Lima, was once the bottom of an ancient ocean. Some 34-41 million years ago, Ocucaje was home to a host of giant creatures, including Miocene dolphins, sharks, and four-legged dwarf whales.
The basilosaurus king lizards are no exception. But the ancestors of basilosaurus were not marine creatures. We know whales are mammals, whose ancestors lived on land.
After that, new whales gradually evolved into semi-aquatic species, that is, half living on land, half living in water. It wasn’t until about 55 million years ago – 10 million years after the great extinction that killed off the dinosaurs – that whale ancestors became fully aquatic, including Basilosaurus.
With a body up to tens of meters long, the name basilosaurus that this whale is given means “king lizard”.
With an average length of 15-20 meters, the basilosaurus was one of the largest animals that ever existed after the Cretaceous-Paleogene extinction event. As mentioned, this whale has a long body, with 70 vertebrae in all, 7 cervical vertebrae, 18 thoracic vertebrae, 20 lumbar vertebrae and 25 caudal vertebrae.
With the midsection of the thorax extending past the anterior caudal vertebrae, basilosaurus had an anguilliform phenotype, meaning it could flex its body and swim like a water snake or sea eel. In addition to the fact that the hind limbs have not completely disappeared, many paleontologists initially mistook it for a reptile.
The hind limb of the ancient basilosaurus whale.
In terms of skull, basilosaurus had a small head and its brain was probably no bigger than a watermelon. This is also a common trait in reptiles like crocodiles – the body size does not match the size of the brain.
Scientists therefore think that basilosaurus was not as intelligent as modern whales and dolphins. They could not hunt in groups and had social behaviors like today’s marine mammals.
Fossil skull of basilosaurus whale.
In return, basilosaurus had a very sharp and extremely strong teeth. The jaw force from its single bite is estimated to be up to 3,600 pounds per square inch (25Mpa equivalent). Analyzing bites from this jaw on other ancient sea creatures, scientists said that basilosaurus only specialized in hunting giant sharks and large whales.
No matter where found, basilosaurus was the premier predator in the waters it reigned. That’s why this whale is called “lizard king” – though again, it’s a whale, not a lizard.
The fossil record that paleontologists have found from the basilosaurus closes around 35-34 million years ago. It was around that time that they thought the whales were extinct.
It coincides with the Eocene-Oligocene extinction event that occurred 33.9 million years ago. Volcanic impacts, meteorites and sudden climate change have wiped out a wide range of terrestrial paleontological species. Under the ocean, the change and disruption of ocean currents also caused many marine animals including the basilosaurus to become extinct.
The basilosaurus left no descendants. Their smaller cousins had better luck escaping and evolving into modern sawtooth and baleen whales. The story of basilosaurus now remains only in fossils beneath the sands of the Ocucaje desert in Peru.
Refer to Phys, Livescience