Long thought to be only a matter of fossil record, extinct for over 60 million years, the coelacanth shocked scientists around the world when it was caught by professional fishermen off the coast of Madagascar. On the other side of the world, a very determined team of cryptozoologists patiently tracked down local legends of a giant fish, until they finally landed a megamouth shark near Oahu, Hawai’i.
Could another living fossil be lurking somewhere in the oceans of the world? Absolutely it could. We know less about the depths of our oceans than we do about the heights of the Himalayas.
Could that living fossil be the largest shark which has ever swum the oceans of this world?
The existing fossil record shows Carcharodon megalodon to have been a massive shark which dominated the oceans some 20 million years ago to possibly as recently as 500,000 years ago. Dating estimates of as recently as 15,000 years ago on some fossilized teeth are now believed to be inaccurate, based on complicating interactions between ocean encrustation and the fossilization itself. (By comparison, the earliest stone tools are believed to have been created roughly 25,000 years ago.) Original guesstimates based on that minimal fossil record estimated it could grow as large as 100 feet long, five times as large as a great white shark. Later, more sober revisions still describe an animal whose jaw can open six feet across, with seven-inch-long teeth, more than twice the size of a great white shark’s. This makes it the second largest predator the earth has ever seen, second only to today’s sperm whale.
Huge shark sightings are not common, but they are also far from rare. Most such sightings are probably those of basking or great white sharks, or possibly of whale sharks. Size is a very difficult thing to estimate when in the water and facing the likelihood of becoming prey. There are no markers against which to measure, other than a fair certainty that the creature is clearly much bigger than the person who saw it.
Thus until such a creature is captured, whether in a net or reliably on film, we can’t prove whether or not it still exists. We can, however, determine whether it is possible for such a creature to have survived. Basically, there has to be adequate food and a consistent temperature and pH.
We can guess that adequate prey exists in the oceans, even for a creature such as this, as demonstrated by the continual survival of the sperm whale. However, it is possible that over the years, the nature of the prey has altered beyond the megalodon’s ability to capture it. In much the same way as the prey of the sabertooth tiger gradually evolved to become small and fast rather than large, strong, and slow, making it increasingly difficult for the sabertooth tiger to hunt successfully, it is possible that an ocean with fewer large, slow creatures would also tend to select for smaller, faster types of shark.
We already know there has consistently been enough oxygen for a fish of that size, since other gigantic gill-breathers continue to thrive. The earth’s temperature has always been such as to allow for ocean thermoclines, so whatever temperature the megalodon preferred, it is likely that it would continue to be able to find it. On an ocean-wide scale, significant changes in pH have not occurred during the relatively short geological period between the height of the megladon’s ocean reign and today. However, both regional pH and salinity and overall average ocean temperature have changed as a result of multiple ice ages. Even if these did not affect the megalodon directly, they may have affected the migratory routes of the megalodon’s major prey, the whales.
Taking all of these factors together, it is highly unlikely that the megaladon has survived. However, if a few megaladons had survived, they would logically tend to gather in the south Pacific, where the migratory routes of the whales intersect the warmer northern waters and where there has been the least geological disruption of ocean waters.
Coincidentally, it is in and around Australia that most of the possible sightings have occurred. Food for thought?