Jana loves compiling and sharing lists about the natural world, science, and history.
1. Stellar Radiation
In 2018, a sad study looked at something that happened a long time ago. Well, it's sad if you love enormous creatures you've never met but still wished they roamed the Earth. In this case, researchers wanted to know what caused a specific and deadly event. Called the Pliocene marine megafauna extinction, it wiped out the sea's monsters. These included the enormous megalodon, which measured up to 25 meters or 80 feet long. Other giants that perished during this time were sea cows as big as whales and big turtles. No, really. These guys would have broken any scale with their weight – 2,200 kilograms or 5,000 pounds.
This large crowd survived for millions of years. Then around 2.6 million years ago, they began dying in massive numbers until the world lost a third of its marine life. What caused this extinction and by default, the answer to megalodon's mysterious end?
The study found evidence that a supernova, possibly even several such exploding stars, detonated at the time of the Pliocene extinction. If they occurred close enough to Earth, the radiation would have affected everything on the planet. Unfortunately, the bigger the animal the more radiation they would have absorbed. Something the size of a human had a fifty percent chance of developing cancer. Thus, the prognosis for megalodon was even worse. Considering that the cancers, mutations and high fatality rates continued for centuries, it's easy to imagine why some species folded.
2. They Lost Their Main Prey
It wasn't hard to find megalodon's menu. Researchers simply looked for fossils that bore the trademark crunch of megalodon's giant teeth. Two species preferred by the shark was an early form of seal and a whale that was around three times smaller than megalodon. Fossils showed that the shark actively hunted or scavenged this baleen whale.
Unfortunately, near the end of the Pliocene Era (5.3–2.58 million years ago), several species of small baleen whales disappeared. A 2017 study concluded that it couldn't have been a coincidence that the shark vanished around the same time. History is full of cases where a predator preferred the meat of a single species and then went extinct after their favorite prey died out. This could have been the case with the tiny baleen whale and megalodon.
Teeth of Terror
3. The Ocean Became Too Hot
In 2018, researchers tested the teeth from modern sharks and megalodon to pinpoint if the extinct giants could thermoregulate their bodies. This ability allows an animal to adapt to its environment's temperature. Today, mako and great white sharks command wide territories because they can handle both warm and cooler environments.
Teeth develop differently depending on the animal's temperature. This allowed researchers to calculate megalodon's average body heat. It was surprisingly hot. To put it into perspective, the ancestors of makos and great whites (who were megalodon's contemporaries) had an estimated temperature of 20 to 30 degrees Celsius or up to 86 degrees Fahrenheit. Megalodon simmered at 35 to 40 degrees Celcius or as high as 104 degrees Fahrenheit. While this was natural for them, the scientists admitted that it was exceptionally warm for a shark.
Global Warming Tipped the Scale
Megalodon's high body temperature suggested that the shark had a fast metabolism. It had to eat a lot to survive. Things took a turn for the worse when climate change warmed the oceans. Megalodon failed to find regular meals because its prey migrated to cooler regions at higher latitudes where the shark did not follow. What could have doomed it, in this case, were a combination of high body temperature, a habitat that started to roast and food scarcity brought severe competition from other predators.
4. The Arrival of the Great White
In 2019, a new investigation found that researchers might have miscalculated when megalodon went extinct. Traditionally, the fossil record suggested that it vanished 2.6 million years ago. However, when scientists re-examined megalodon remains from different regions they found something curious. There's no doubt that the species were alive and well for millions of years, but then around a million years before their official extinction date, all clear signs of their presence turned murky. It's not unknown for older fossils to move to younger rock, which often causes scientists to date the animals to a period they never actually lived in.
There is a chance that megalodon never died during the Pliocene marine megafauna extinction. Instead, it bowed out a millennia before the disaster. If their real extinction occurred 3.6 million years ago, then megalodon briefly overlapped with great white sharks which evolved 4 million years ago. For the next 400,000 years, the smaller species successfully spread across the globe, invaded megalodon's territory and if researchers are correct, great whites were also smarter. Their success as a species could have made it hard for megalodon to flourish and eventually the giants lost the battle against the new guys.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2019 Jana Louise Smit