Megalodon was big and lived long life
When you think of the largest carnivores, you might think of lions on land or killer whales in the sea, but in Earth’s past, there have been much larger meat-eaters.
One of the largest was the megatooth shark, commonly called Megalodon. Through the years, it has gone through several changes in its scientific name, including Megaselachus, Procacharodon and Carcharocles. The currently accepted name is Otodis megalodon.
Although some exaggerated estimates put its size at 65 feet, a more likely maximum length is 50 feet, twice the size of today’s largest predatory shark, the great white. The size was calculated based on its teeth, using equations developed by comparing teeth to body length for 13 living species of related sharks, a group that includes the mako and the great white.
Megalodon teeth are found in shallow marine sediments formed in temperate conditions — neither very warm nor very cold water — worldwide, including Europe, Africa and Australia. Here in North America, favorite hunting grounds are the Calvert Cliffs in Maryland, the phosphate mines around Aurora, North Carolina, and the beaches and estuaries around Venice, on Florida’s west coast.
The largest known Megalodon tooth is 6.3 inches long. It used such teeth to feed on seals and whales, as shown by bite marks on fossil bones of those animals.
Some recent research has given us a better sense of not only its size but also its lifespan and breeding habits.
Most information about prehistoric sharks comes from their teeth, which is usually all that becomes fossilized because the rest of their skeleton is made of cartilage, the flexible material in your nose and ears, which doesn’t fossilize well. Occasionally shark vertebrae become calcified, leading to their preservation.
The recent research looked at the only known relatively complete calcified vertebral column known for Megalodon. It consists of 150 vertebrae of a Miocene specimen from Belgium that came from an individual estimated to have been about 30 feet long.
Shark vertebrae have annual growth lines. Analyzing those, the scientists deduced that it was born large, about 6 1⁄2 feet long, grew at an average rate of about 6 inches a year, and died at age 46. The largest individuals probably had a lifespan of 88 to 100 years.
The large size at birth is common among that group of sharks due to something called intrauterine cannibalism, in which some embryos eat their brothers and sisters before birth, resulting in fewer but larger individuals being born.
Megalodon lived from the middle of the Miocene Epoch to the early Pliocene, 14 million to 4 million years ago. Despite media hype, there is no evidence that it exists today.
Some have suggested that maybe it still lives in the depths of the oceans and we just haven’t found it yet. That is unlikely. The ocean food chain is based on small photosynthetic organisms that live in shallow water, where they can harvest sunlight. In the depths, there would not be enough food for such a large, active predator as Megalodon.
Gnidovec.1@osu.edu