Megalodons, known scientifically as Otodus megalodon, were huge sharks that grew to 50 feet in length and traveled the oceans between 15 and 3.6 million years ago, said study author Kenshu. Shimada, professor of paleobiology at DePaul University in Chicago.
The 6.6-foot measurement is fairly accurate and aligns with other discoveries in megalodon nurseries in Panama and Spain, said Jack Cooper, a fossil shark researcher and doctoral student in the biosciences department at Swansea University in Wales. United Kingdom, which did not participate in the study.
The study is significant because there is not much research on megalodon reproduction, he said.
To find the length of the animal at birth, researchers examined computed tomography scans of the vertebrae of a megalodon that were originally found in Belgium in the 1860s. Like the rings of a tree, the vertebrae of ‘a megalodon have annual growth bands that allow scientists to track the age of the shark.
The specimen was believed to be 46 years old when it died, so Shimada counted the growth bands up to the birth ring and calculated the length of the animal at birth. This shark was estimated to be about 30 feet long.
Survival of the fittest
These extinct sea creatures did not grow so large in the womb fortunately.
As they grew inside their mother, megalodons would eat other undiscovered eggs, which is known as intrauterine cannibalism.
“The consequence of egg-eating behavior is that only a few puppies will survive and develop, but each of them can be of considerable size at birth,” Shimada said.
Its large size at birth reduces the chances of megalodon babies being eaten by other predators.
Some modern sharks that are part of the order Lamniformes (the same one to which megalodons belong) also practice this behavior.
Sand tiger sharks eat other eggs in the womb and Shimada said they sometimes eat other hatched siblings as well.
He says sand tiger sharks cost a lot of energy to raise such large babies, but, similar to the megalodon, this evolutionary strategy reduces the chances of eating them after birth.
Looking ahead
Much is still known about the giant shark, said Shimada, who wants to find out more. He has been interested in the megalodon since he was 13 when he found a 2-inch megalodon tooth at a geological site on the outskirts of Tokyo.
Although this study has revealed many things about the birth of a megalodon, the specimen was only 46 years old, which is the average age of this animal.
Shimada hopes to investigate the last years of the shark, which is estimated to be between 88 and 100 years old, to find out its growth pattern.