A groundbreaking study proposes that the impressive size attained by megalodons was a result of intrauterine cannibalism, challenging the previously accepted theory that their warm-blooded nature was the primary factor. Recently featured in the Historical Biology scientific journal and reported by Science News, a team led by paleobiologist Kenshu Shimada from DePaul University delved into the mystery of megalodon gigantism.
The prevailing belief attributed megalodons’ colossal size to their warm-blooded physiology, theorizing that elevated body temperatures enabled them to pursue faster and more energetic prey, ultimately contributing to their overall mass. While the team acknowledges the significance of warm-bloodedness in megalodons, they contend that there must be more to the story.
In 2018, Shimada’s team published a report emphasizing the enormous size of megalodon teeth, the only remnants available for study due to the shark’s cartilaginous body composition. The team’s analysis suggested that megalodons reached lengths of at least 14 meters, double that of any non-filter feeder shark. Intriguingly, other extinct species displaying gigantism, akin to megalodons, were notably shorter, around six meters in length.
This glaring contrast prompted Shimada’s team to explore unconventional explanations, leading them to the hypothesis of intrauterine cannibalism. Megalodons, like many sharks, reproduce through ovoviviparity, a process where embryos develop inside eggs within the mother’s womb until hatching. The first pup to hatch often engages in intrauterine cannibalism, consuming its siblings, resulting in a larger and more self-sufficient newborn.
The study suggests that this reproductive strategy, coupled with favorable environmental conditions such as water temperature and abundant food sources, facilitated the extraordinary growth of certain shark species, including the megalodon. However, some experts, like Calvert Marine Museum paleontologist Stephen Godfrey, remain skeptical, emphasizing that this theory doesn’t fully explain the megalodon’s greater gigantism compared to other large shark species.
University of Bristol paleontologist Humberto Férron offers a nuanced perspective, proposing that megalodon evolution into gigantism likely involved a combination of factors. He mentions that reproductive strategy, endothermy, and abundant prey collectively contributed to their colossal size. Despite the extinction of the megalodon species, the study opens new avenues for understanding their evolutionary history and challenges previously held notions about the drivers behind their remarkable size.