Some fossil whales are not as boring as they may look as a new study suggests!

I have not written for a while now, but I am back and many new discoveries have been made during may absence from the Internet. I am not usually one to cover new discoveries since they tend to get covered in enough detail on other blogs and websites, but the particular discovery I am about to describe to you is particularly interesting to me. A long time ago I did some research into giant predatory sperm whales of the Cenozoic era. Just a passing whim of interest. The idea of giant predatory whales with Tyrannosaur size teeth seemed rather contradictory to their modern appearance as rather boring (sorry for my opinion) mild mannered filter feeders. Anyway I wrote a summary of my research to go on my blog (which at the time was non existent), so I saved it and forgot about it. I will display it here since it is relevant to this particular discovery and will provide some background info:

The Miocene, a bad time to be Megalodon.

Scientists have always thought that the giant great white shark Megalodon was the apex predator of the oceans from 16-1.6 million years ago. It had jaws large enough for a man to walk through and teeth the size of carving knives. It was supremely adapted for taking down the largest marine mammals. There is mounting evidence to prove that Megalodon was a whale killer, bones have been found with Megalodon teeth embedded within them. Unfortunately the mammals began to fight back with new and highly evolved macro predators.

First and foremost was Acrophyseter, a sperm whale from Peru with huge teeth on the upper and lower jaws. Brygmophyseter from Japan was up to 12 meters in length and had teeth as large as Tyrannosaurus. Zygophyseter from Italy was another killer sperm whale. There was also Orcinus citoniensis. A smaller but toothier version of the modern killer whale. And last but not least Pelagiarctos, the killer walrus. All of these animals were thought to have been preyed on by Megalodon., the biggest shark of all time. I am suggesting otherwise, all of these animals were just as capable of eating Megalodon as Megalodon was capable of eating them.

The killer sperm whales were probably the most terrible predators of young and fully grown Megalodon. Unlike modern sperm whales they had teeth on the upper and lower jaws which allowed them to do much more damage when biting. Brygmophyseter and Zygophyseter had relatively slender jaws suggesting they would have mainly fed on juvenile Megalodon. They probably hunted in packs, using sonar to stun their victims and their heads to ram into the side of their prey. A killer sperm whale skull from California (which is yet to be named) has a much more robust skull. This would have given it a much more powerful bite and may have allowed it to take on a fully grown Megalodon.

The juvenile Megalodon were the easiest targets, smaller or equal in size to the orcas. Today orcas hunt young whales. It usually takes hours for the hunt to finish, often the orcas injure the calf until it is too weak to defend itself and then wait slowly for it to die. Prehistoric orcas and sperm whales probably did something similar with Megalodon, however sharks are not air breathers and would be capable of diving deeper than the orcas. The prehistoric whales probably hunted using a combination of tactics used by modern whales for both fish and larger prey.

When hunting juvenile Megalodon, which lived close to shore, the whales probably would have driven the sharks towards the coast, trapping them against the shore. Dolphins do this with fish today. Unlike dolphins these prehistoric whales probably finished the sharks off, using a similar method to modern orcas as mentioned above or by driving the sharks up the shore like sea lions and thrashing them to pieces . In deeper water the whales would have swum below the unsuspecting Megalodon, slowly driving it towards the surface. Like modern whales they may have breathed out rings of bubbles to confuse and contain the shark. Then diving in and out of the bubbles from all directions ramming and biting until the shark was dead. The meal was probably then shared with the rest of the pod.

One animal that I have not yet mentioned is Pelagiarctos. No way near big enough to take on a fully grown Megalodon, but perfectly capable of hunting juveniles. Like modern walruses it was probably a sociable animal, hunting in groups to bring down prey. Walruses are known to have eaten seals, however Pelagiarctos was s specialized carnivore, possessing shearing and slicing teeth. It probably jousted juvenile Megalodon with its tusks, creating deep wounds. However Pelagiarctos was not completely indestructible as a fully grown Megalodon would make short work of its blubbery body.

Today Megalodon and all of these hideous mammals are extinct (phew). But the ancestors of the small Orcinus citoniensis have now evolved into the bigger Orcinus orca which possess larger teeth and are perhaps the dominant predators in today’s seas. They still carry out the work of their ancestors, for orcas have been observed killing fully grown great white sharks, so beware next time you take a dip, for you may have a nasty surprise.

Of course there is a lot of speculation and invalid imagination regarding the hunting tactics of marine predators in the article above; considering the fact that most of these animals were smaller or of equal size to a Megalodon it is unlikely that the whales actively hunted these monstrous sharks, and more likely that they only used their weapons against it in self defence, but on the whole it just provides to set the scene.

Above; Leviathan was the same size as a modern sperm whale.

Now however; scientists in the Peruvian desert have discovered a monster that was even bigger than the 16 meter long Megalodon shark. They have named it Leviathan, after the mythical sea monster referred to in the bible and many other books. This animal was no shark, but an 18 meter long sperm whale with 1 foot long teeth. Megalodon did have a powerful bite according to recent studies using computer modelling, but these remain inconclusive since the only model we have is the skull of a modern day great white and some teeth of the Megalodon. The study estimates a maximum bite force of 40,000 pounds. To give an idea of scale Tyrannosaurus is estimated to have a bite force of 68,000 pounds!

Above; Leviathan was discovered in 2008 by a palaeontological expedition into the Peruvian desert.

Unlike Brygmopgyseter and the other killer sperm whales mentioned before; Leviathan was bigger than Megalodon and therefore capable of attacking it easily. Because Megalodon had cartilage jaws and loosely set teeth, where as Leviathan had bone jaws firmly attached to the cranium and firmly set teeth much larger than those of Megalodon it clearly had a more powerful bite. Possibly in the region of that of a Tyrannosaurus rex. Megalodon teeth get to about 15-18 cm at their largest. Leviathan teeth are 30 cm long!

Above; a Megalodon tooth.

Leviathan probably deployed completely different hunting tactics to Megalodon as well. The teeth of Megalodon are for slicing; they are flat and serrated. In Leviathan and other sperm whales they are round and conical. This suggests that Leviathan killed by grabbing onto prey and crushing it. Megalodon, as in modern sharks, must have killed by biting chunks from its victims. The jaws of sharks are separate from the rest of the skull allowing them to extend them outwards as they bite into prey. This is taken to the extreme by the modern day goblin shark.

Above; the skulls of Leviathan (top) and the modern sperm whale (bottom). Observe that in the modern sperm whale the upper jaw lacks teeth and the lower jaw is rather slender compared to that of Leviathan.

Compared to modern sperm whales the skull is much broader and the lower jaw is thicker suggesting that it was a much more powerful predator. Tooth sockets and remains of other related killer sperm whales tell us that Leviathan had teeth on its upper jaw unlike modern sperm whales. Considering the fact that a modern sperm whale will happily take on 15 meter long colossal and giant squids you wonder what manner of prey the Leviathan was eating!

Most probably other whales. The reason why its discovery is, however, significant is because this is the largest killer sperm whale ever found. The skull of Acrophyseter for example is only just over 60cm in length. The skull of Leviathan is in the order of about 2 meters in length. It is evident that this animal was more dangerous than any Mosasaur, Ichthyosaur or shark that ever lived. It combined almost human intelligence (assuming that this animal shares the intelligence of its modern day relatives) with brute force and strength must have been terrifying. So we must ask: Why are modern sperm whales so comparatively slender and why did the killer sperm whales die off?

This most probably correlates with the progressive general trend of cooling ever since the KT extinction. This certainly drove Megalodon extinct. As its warm hunting grounds were gradually encroached on by cold arctic waters the whales could take refuge near the poles. More likely is that the cooling caused the ice sheets to take up more water and began the destruction of the shallow Peruvian sea that supported Megalodon and Leviathan. As for the other killer sperm whales I am lost as to the cause for their demise. Perhaps big teeth were no longer needed for protection from Megalodon; arguing against them being predators of this giant shark. Lack of preliminary research prevents me from coming to a reliable conclusion.