A new study suggests that the Megalodon shark was more of a slow swimmer that relied on its warm-bloodedness for nutrient digestion and absorption. The notorious Megalodon, or the ‘megatooth shark,’ is best known for its gigantic size and deadly reputation.
This study was led by Professor Kenshu Shimada, a paleobiology professor at DePaul University, along with his team of researchers. It presents an entirely different understanding of the lifestyle and biology of Otodus megalodon.
This fossil shark, living nearly worldwide from about 15 to 3.6 million years ago, reached a length of 65 feet (20 meters) at its maximum.
The research was conducted based on tiny scales, accurately referred to as ‘placoid scales.’ Researchers found these scales within rock pieces that surrounded a previously described tooth set of the fossil shark from Japan. These seemingly insignificant scales have now opened up a new perspective on Megalodon.
As Professor Shimada put it, “Our big scientific findings come from ‘tiny evidence’ as small as grains of sand.”
Earlier, understanding the biology of O. megalodon was mostly based on its massive teeth and vertebrae. It was widely believed that O. megalodon, being partially warm-blooded or regionally endothermic – like the large active modern predatory sharks such as makos and great white sharks – was a swift and active swimmer.
This new study, however, counters this assumption. It indicates that the small placoid scales of the Megalodon lack the narrowly-spaced ridges or ‘keels’ typically found in fast-swimming sharks.
“This led my research team to consider O. megalodon to be an ‘average swimmer’ with occasional bursts of faster swimming for prey capture,” explained Shimada.
This revelation gives rise to a new paradox. A recent study, in which Shimada also played a significant role, has provided substantial support for the presence of regional endothermy in O. megalodon.
However, the question arises: how did the fossil shark expend the high level of metabolic heat generated by its warm-bloodedness if it wasn’t a fast swimmer?
After examining existing literature, the research team discovered an overlooked aspect of endothermic body physiology that could answer this question. This involves facilitating digestion and absorbing and processing nutrients—an aspect that hadn’t been considered in the biological context of O. megalodon.
“It suddenly made perfect sense,” Shimada said, going on to elaborate, “Otodus megalodon must have swallowed large pieces of food, so it is quite possible that the fossil shark achieved gigantism to invest its endothermic metabolism to promote visceral food processing.”
Therefore, the Megalodon, in reality, might have been less of a terror of the seas. More than likely, it was a slow, steady cruiser. Megalodon utilized its warm-bloodedness not for speed, but for efficiently processing its food and absorbing nutrients.
The research promises to further our understanding of these magnificent creatures of the past and the evolutionary mechanisms that drove them.