Megalodon Babies Grew by Eating Unhatched Eggs in Womb, Study Finds

New research released Sunday suggests Megalodon shark pups were born larger than most human adults, about 6.6 feet long, and feasted on unhatched embryos to reach such a large size.

Identified annual growth bands in a vertebra of the extinct megatooth shark Otodus megalodon shown with hypothetical silhouettes of the shark at birth and death, each compared with the size of typical adult human. (Credit: DePaul University/Kenshu Shimada)

(CN) — As with most prehistoric sharks, little is known about their biology or behavior as the information scientists do have mainly comes from fossilized teeth, despite the animal leaving behind an otherwise rich fossil record. Those teeth are thought to have been able to exert an incredible 24,000 to 41,000 pounds-per-feet of bite force — more than enough to crush bone.

Researchers looked closely at a set of rare vertebral remains housed in the Royal Belgian Institute of Natural Sciences using a novel CT scanning technique. They were interested in “incremental growth bands” found in the shark’s vertebra which they believe to be analogous to the annual rings used in determining the age of trees. The team released their findings in a new study published Sunday, Jan. 10, in the journal Historical Biology.

“As one of the largest carnivores that ever existed on Earth, deciphering such growth parameters of O. megalodon is critical to understand the role large carnivores play in the context of the evolution of marine ecosystems,” said lead author Kenshu Shimada, a paleobiologist at DePaul University in Chicago, in a related statement.

By examining these growth bands, researchers determined the species had an average lifespan of at least 88-100 years, and grew about 6.2 inches annually for the first 46 years. 

The Megalodon isn’t thought to have experienced any significant growth spurts, rather they probably grew at a relatively even pace until reaching the age of 46. That ranks them among the largest and longest living carnivores ever to roam the Earth.

Based on the upper end of their measurements, researchers theorize that the Megalodon could have had a jaw-dropping theoretical lifespan of roughly 500 years. However, they admit the number may be an overestimation due to imprecise measurements.

The specimen examined had 46 growth bands, meaning it died at age 46, at a size of about 27 feet long. Researchers were able to back-calculate its length by measuring each band and believe it was over 6 feet long at birth.

The data also suggests that these pups may have feasted on the unhatched eggs of their siblings in addition to embryos, as modern-day sand tiger sharks do. It’s thought that their large size provided an evolutionary advantage by reducing the chance that another predator could eat them shortly after hatching.

“Results from this work shed new light on the life history of Megalodon, not only how Megalodon grew, but also how its embryos developed, how it gave birth and how long it could have lived,” said co-author Martin Becker, a professor in the department of environmental science at William Patterson University in New Jersey, in a related statement.

Because of their gargantuan size and wide-ranging habitat, it’s likely the Megalodon exerted heavy evolutionary pressure on the development of fellow marine life. These other marine animals would have been forced to evolve and adapt to fend off, or more likely to avoid, such a fierce and wide-ranging predator, so much of the sea life around today likely adapted in-part to counter this ancient foe.

“Understanding the life-history traits of large marine carnivores, including growth patterns, is important to elucidate the effect of these predators on their ecosystems and population dynamics of organisms,” explain the authors in their study.

“Yet, deciphering the life-history strategy of prehistoric sharks is often challenging because the vast majority of species are represented by teeth, as their poorly mineralized cartilaginous skeleton usually does not fossilize. In this regard, our vertebra-based study is a rare exception, where the life-history traits for Otodus megalodon proposed here have a significant bearing on various hypotheses and biological issues.”

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