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  • Imagine swimming in the ocean. You're  splashing around, minding your own business,  

  • when all of a sudden a shark fin the size  of a boat pops out of the water and heads  

  • straight towards you. That would probably be  the last time you stepped foot in the ocean,  

  • if you made it out alive that is. The only  shark that could have a dorsal fin of that  

  • size would belong to a megalodon. Luckily  for youand all of usthe megalodon went  

  • extinct around 3.6 million years ago. But what  caused this massive apex predator to die off?  

  • And is there a chance that it is still  lurking in the depths of the oceans?

  • The megalodon or Carcharocles megalodon first  inhabited the oceans of planet Earth around  

  • 23 million years ago. They were the largest  shark to ever live. Megalodons varied in size,  

  • but studies suggest that on average a female  meg could be between 45 and 59 feet long. This  

  • range varies so widely because scientists need  to extrapolate the size based on teeth and jaw  

  • fragments found in the fossil record. At this  point in time a full megalodon skeleton has not  

  • been found. However, from the remains we do haveit is clear that these creatures were enormous.  

  • Adult megalodons had no predators because  of their massive body size. The shark's  

  • main prey was small whales. That's rightthey ate whales, that's how big they were.

  • Megalodons roamed every ocean of  the world, although they stayed away  

  • from the polar regions where the water would  be too cold. What we know about the megalodon  

  • species comes from fossil remains, and scientific  observations of their much smaller relatives that  

  • live today. The largest predatory shark  species alive today is the great white.  

  • The largest great white ever recorded  was around 36 feet long. This makes it  

  • 20 feet shorter than the megalodonMegs were truly massive sharks.

  • Megalodons were incredibly successful at what  they did. They outcompeted other predators for  

  • about 20 million years, and stayed at the top of  the food chain for that entire time. Their size,  

  • razor sharp teeth, and speed allowed them to  hunt and kill prey with deadly efficiency. So,  

  • what caused the Megalodon to go extinct? Why isn't  

  • this incredibly successful killing  machine ruling over the oceans today?

  • There were probably several factors, but evidence  points to a few clear changes that had a big  

  • impact on the megalodon survival rate. Between  3 and 5 million years ago the climate began to  

  • change on planet Earth. The world began to cool  as it entered the epoch known as the Plioscene.  

  • As global temperatures dropped the oceans were  affected. One major change that occurred as  

  • temperatures cooled was that the sea levels  began to drop. This happens during ice ages,  

  • and periods of cooling, because the water of  the oceans gets trapped in ice and glaciers.  

  • As water gets converted into its solid form,  

  • it is removed from the oceans. This  causes the overall sea level to drop.

  • The dropping of the global sea level wouldn't  have been a problem for megalodon if that was  

  • the only change that occured, but when the  sea level dropped, new land started to form  

  • that had previously been underwater. During  the Pliocene the Isthmus of Panama began to  

  • take shape. The collision of tectonic plates in  the area caused volcanic activity that resulted  

  • in the formation of the mountains that  now stretch from North to South America.

  • The emergence of this new land that connected the  Americas had a huge impact on the animals of the  

  • oceans. The land that would become Central America  had been under water for millions of years,  

  • meaning that there was nothing blocking marine  species from crossing between what would become  

  • the Atlantic and Pacific Oceans near the equator.

  • Once the access between the Americas was blocked  off by land, many species were now stuck either  

  • on one side of the continents or the other. This  meant that access to some of megalodon's prey may  

  • have been separated from them. Ocean currents and  movement of nutrients in the oceans began to shift  

  • once the equatorial connection between the oceans  was impeded. This would have caused species to  

  • migrate to new areas, or if they could not adjust  to the new environment they would go extinct.

  • The currents and nutrients that once flowed  between the Americas would have been abruptly  

  • brought to a halt. Without these nutrientsbiodiversity would drop. This change would  

  • have a domino effect on all species living  throughout the oceans. Nutrients would no  

  • longer be where they once were, and entire  ecosystems would have vanished. This alone  

  • would have caused mass extinctions of aquatic  organisms, leaving room for new species to evolve.

  • Even if this lowering of ocean levelsand the blockage between the oceans,  

  • did not directly cause megalodon to go extinctit most likely had an impact on their prey.  

  • Since megalodon was large and slow to  reproduce, it filled one specific niche,  

  • that of apex predator. If the environment  suddenly changed, it was unlikely that  

  • megalodon had the genetic diversity to  adapt to a new environment with less prey.

  • Another impact of the lowering of ocean levels  is that the oceans become saltier. As more  

  • and more water is trapped in ice and glaciers  the salt to water ratio in the ocean changes.  

  • The salt does not get trapped with the water, so  salt levels remain constant, while water levels  

  • decrease. This causes an increase in salinity  throughout parts of the oceans. The difference in  

  • saltiness would have shifted the ocean currentsand nutrient cycles, ever more. In fact,  

  • this change in salinity is one of the main  reasons we have the ocean conveyor belt of today.

  • All of these changes to the  oceans would have meant the  

  • environment that the megalodon had been  so successful in for millions of years,  

  • was now different. It is very difficult for large  specialist predators to adapt to changes in their  

  • environment. Think about what is happening in  the arctic right now to polar bears. They are  

  • highly specialized for the environment they  evolved in, but if the ice continues to melt,  

  • and global temperature continues to rise, they  will go extinct. The polar bear species just  

  • does not have enough genetic diversity to allow  them to be successful in a warmer environment.

  • As the environment changed during the Pliocenemarine diversity diminished for a while before  

  • natural selection caused new species to evolve  and thrive. Unfortunately, this would have taken  

  • thousands and thousands of years; time that the  megalodon did not have. With less biodiversity,  

  • and animals to eat, all predators in the  ocean would need to compete for similar  

  • food sources. The prey that megalodon  once thrived on would have diminished,  

  • which meant that either they had to compete for  a different food source, or starve to death.

  • Before the change in the environment of the  Pliocene, the oceans were filled with large marine  

  • animals. Many of these animals ate krill or small  fish like the baleen whales of today. This meant  

  • that there was an abundance of prey for megalodon  to hunt. However, after the climate shift  

  • organisms such as toothless walruses, aquatic  sloths, and dwarf baleen whales did not survive  

  • into the new environment. Slowly, but surelythe megalodons variety of food was diminished.

  • This is where the real problem for megalodon came  in. Changing of climate most likely contributed  

  • to the extinction of the species, but scientists  now believe there was one main culprit that drove  

  • the nail into the coffin of the megalodon. At  around the same time as megalodon went extinct,  

  • a new apex predator had just started to  make its appearance, the great white shark.

  • Carcharodon carcharias, or the great white  shark, appeared around the same time as the  

  • megalodon species began to decline. It would seem  this new species of shark could out compete the  

  • megalodon. The smaller size of great whites  allowed them to catch and eat smaller prey,  

  • which was more abundant after the climate shiftThe ability to eat many different species,  

  • other than just small whales, gave  the great whites an advantage.

  • Not only did the great white have a wider  variety of food it could choose from,  

  • but the smaller body size actually worked in its  favor. Since the megalodon had such a massive  

  • body it needed to stay in relatively warm watersso that it could maintain its body temperature.  

  • Sharks are ectotherms meaning that they don't  regulate their internal body temperature,  

  • but instead, rely on factors such as sunlight  and muscle movement to increase the temperature  

  • of their bodies. The smaller bodies of the  great white sharks meant they could venture  

  • into cooler waters, since they had less body  mass to keep warm. Their muscles did not need  

  • to work quite as hard as megalodon to keep  their body temperature up, and therefore,  

  • they didn't need as much energy from  food as their larger cousins either.

  • It was also likely that great whites hunted  some of the same prey as megalodon. Perhaps  

  • the great whites targeted the young of  the species that megalodon was hunting,  

  • thus reducing the amount of adult prey available  for the megalodon to eat. The great white sharks  

  • were by no means trying to outcompete and cause  the megalodon to go extinct, but they were,  

  • and still are, very efficient predators, who  in the new ocean environment thrived. The great  

  • white shark's success most likely played a role  in the extinction of the once great megalodon.

  • Scientists also think that the evolution of other  smaller species of shark could have put pressure  

  • on the megalodons. For example, tiger sharks  which lived during the same time as megalodon,  

  • and in very similar environments, may have  contributed to the larger shark's demise.  

  • It has been suggested that great whites and  tiger sharks may have fed on megalodon young  

  • that had not grown to their full size  yet, causing even fewer numbers of the  

  • species to reach maturity. As we gather more  evidence, we may find that megalodon was not  

  • just outcompeted by smaller species of shark, but  their babies may have been hunted by them as well.

  • One theory of what caused the megalodon  to go extinct is really out there,  

  • literally. Some astronomers suggest that  a supernova may have contributed to the  

  • extinction of the largest sharks that ever livedThe claim is that a nearby star went supernova,  

  • enveloping the Earth in harmful muon radiationThis radiation would have been harmful to many  

  • species. But ones that reproduce slowly like the  megalodon, would have been affected much more  

  • drastically because of the build up of mutations  and lack of genetic diversity in the species.

  • All of these factors may have played  a role in the extinction of megalodon,  

  • but are we so sure that the species is really  extinct? Could there be a gigantic 60 foot shark  

  • lurking in the blackness of the oceans? Welllet's look at the evidence. Humans have been  

  • exploring the oceans, and recording their  observations, for hundreds of years. In all  

  • that time there have been no reliable accountsor documentation, of megalodons being sighted.

  • If megalodons were still alive, we would at  least expect to find whales or other prey  

  • with 10 foot bite marks on them from the jaws ofmegalodon. But such evidence has never been found.  

  • We would also expect to find at least some  megalodon fossils in layers of the Earth  

  • younger than 3.5 million years old, but to  this day no such fossils have been found.

  • Scientists also believe that megalodons  established nurseries for their young in  

  • shallow seas, which means that we should see  baby megalodons near the surface of the ocean.  

  • Even a baby megalodon would be a massive sharkand would most definitely make the news. Yet,  

  • this has never occurred. It is important to  remember that for any species to continue on  

  • it needs to reproduce, and megalodons, like  all sharks and animals, don't live forever.  

  • The fact that there has never been a reliable  sighting of a full grown, or baby megalodon,  

  • is a good indication the  species went extinct long ago.

  • Megladon also likely hunted in  shallower waters or near the surface,  

  • because that was where their food source livedWhales are mammals, and therefore need to come to  

  • the surface to breath air. It would seem highly  improbable that a megalodon would wait until a  

  • whale dove into the far far depths of the ocean to  attack it. For one thing, how would the megalodon  

  • see its prey in the deep ocean where no light  reaches? Sharks have a very keen sense of smell,  

  • but they still rely heavily on their eyes  to attack prey once they are within sight.

  • So, no, there are no more megalodon left in the  oceans of planet Earth. And to be fair, it's  

  • probably better that way. I don't know about youbut I would be much more hesitant to go swimming,  

  • or get in a boat, if I knew there was a fifty  foot killing machine swimming around the ocean.

  • Now watchYOU vs THE MEG - How  Can You Defeat and Survive It  

  • (The Meg Shark Movie).” Or check outCROCODILE  vs GREAT WHITE SHARK - Who Would ACTUALLY Win?”

Imagine swimming in the ocean. You're  splashing around, minding your own business,  

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The Why and How of the Megalodon Extinction (What Killed the Giant Shark)

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    Summer posted on 2021/05/07
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