(MENAFN – The Conversation) Made famous by blocker 2018 The Meg, the largest predatory shark ever discovered, the megalodon, is a mystery. We know that it lived between 15 and 3.6 million years ago and reached at least 14 meters in length, more than twice the size of a large white adult. But learning more about the great shark requires some detective work.
Because of its soft cartilaginous skeleton, only a few parts of the shark’s body are mined and preserved, including teeth, skull and spine. This means that the fossil record is very poor for this animal. Not surprisingly, the predator’s 17cm teeth have received much attention from researchers. But in a newly published study, Professor Kenshu Shimada of DePaul University and colleagues called for ads elsewhere.
By examining the spine of the now-extinct megalodon, the team found that it gave birth to a baby two meters long, larger than an adult. It was just as the babies grew so big probably as a result of cannibalism, eating their unborn sisters in the womb.
Mystery in the spine
Like humans, the backbone is made up of many parts called the vertebra, which grow as the animal gets older. The researchers measured a megalodon vertebra from the Miocene epoch, which lasted five to 23 million years ago.
Comparing it to today’s giant white sharks, the team thought the megalodon it came from was about nine meters long when it was alive, but they didn’t stop there. Basking sharks deposit rings of hard material on the vertebra each year, and as tree stock they can be used to estimate age.
To count these rings inside the scientists would have to cut through the fossil, damaging it forever. The solution was to use a detailed X-ray scan to examine the internal structures, without causing any damage to the priceless sample, revealing that this shark died while he is 46 years old.
Megalodon babies grew larger than adults by eating their sisters in the womb. DePaul / Kenshu Shimada University
Looking down through the rows, the team can see how big this vertebra was when the shark was born. Surprisingly, the size estimate at the first growth ring means that the shark was two meters at birth, meaning it was larger than an adult at birth.
Some sharks lay eggs, while others lay young alive. In most sharks, however, the eggs lay inside the mother, where the young eat the egg yolk and the filters she empties until they are born fully formed.
The large birth size estimate for this particular megalodon provides strong evidence that this species had the same reproductive mode, with a large investment in a smaller number of large offspring. The dark secret is the megalodon, in order to achieve this size in the uterus, the developing young must have eaten a lot.
Read more: The Meg: the ocean fossil record is a treasure trove of potential monster movies
Eating their brothers
It is very likely, this new study argues, that infant growth was stimulated by cannibalism of their unborn sisters, a sinister conveyor belt of high-protein flavors for hungry puppies.
It is not known for sure how many megalodon embryos were extracted. In sharks today, millions of eggs are formed and sent to fertilize. The hatched embryos start eating the eggs around and in some cases, like the sand tiger shark, they eat other embryos as well. Sharks can hold one or more pups in each of their two uteri, so it is likely that at least two megalodons were born at the same time.
This grim way of life is not unique. All living sharks of the lamniform order, a group that includes large white, mako, and more likely sharks, use this strategy, which has been in place for at least 70 million years .
This study also roughly estimates the life expectancy of the species at 88-100 years of age, using their dorsal data and established tooth growth patterns. This is in line with the estimated ages for great white sharks and whales, just falling short of the fastest breaking record for 500-year-old Greenland hens, which are known to live in the slow stretch of cold northern oceans.
The beginning of megalodon life seems to have been the beginning of two halves. They were protected by a wonderful mother sacrificing time and energy to her pups, while doing damage in the womb.
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