Megalodon’s Size and Shape Reveal Insights into Aquatic Vertebrate Gigantism

CHICAGO — A recent groundbreaking study led by paleobiology professor Kenshu Shimada from DePaul University has shed new light on the biology and morphology of the formidable prehistoric shark, Otodus megalodon. Often sensationalized in popular media and portrayed as a monstrous version of the modern great white shark, scientific understanding of Megalodon has been primarily based on sparse fossil evidence, particularly teeth and vertebral remains. This fresh research effort involving an international team of experts aims to refine our understanding of this majestic marine predator that roamed the oceans approximately 15 to 3.6 million years ago.

The study, co-authored by 28 specialists in shark anatomy, fossil discovery, and vertebrate biology from various corners of the globe, offers several innovative insights into the structure and life history of Megalodon. As advancements in paleontological methods evolve, researchers can make better use of comparative analyses between modern-day shark species and fossil evidence, forming inspired hypotheses regarding the features of these long-extinct creatures. The findings from this pivotal research are set to be published in the eminent journal, Palaeontologia Electronica.

Historically, the sheer size of Otodus megalodon has attracted considerable fascination. Earlier interpretations often showcased the species as a colossal version of the contemporary great white shark, Carcharodon carcharias. However, this study has sparked a shift in thinking, leading scientists to consider alternative models based on empirical data rather than mere speculation. The researchers based their conclusions on a unique comparative analysis that encompassed over 145 modern and 20 extinct shark species, allowing for a comprehensive understanding of body proportions, sizes, and possible anatomical structures.

One of the significant discoveries of the study includes the analysis of a nearly complete fossilized vertebral column found in Belgium. This “trunk” fossil, measuring roughly 11 meters in length, served as a crucial reference point for estimating the overall size of the individual Megalodon. By considering the average proportions of other sharks, the research team estimated that the head and tail lengths of a corresponding Megalodon would be approximately 1.8 meters (6 feet) and 3.6 meters (12 feet), respectively. With these data, the total body length of the individual in question was recalibrated to roughly 16.4 meters (54 feet).

Intriguingly, the researchers also evaluated larger vertebrae thought to belong to other Megalodon individuals found in Denmark. These specimens, which may measure up to 23 centimeters (9 inches) in diameter, suggest the potential existence of even larger Megalodon specimens, with estimates nearing an astounding 24.3 meters (80 feet). According to Shimada, such measurements are scientifically justified and represent the largest possible reasonable estimates based on the fossil record currently available.

Delving deeper into the implications of their findings, the research team posited that Otodus megalodon likely bore a closer resemblance to the more streamlined body shape of modern lemon sharks than the robust structure of great white sharks. This revelation could significantly influence how scientists understand the evolutionary adaptations of gigantic aquatic predators. In fact, the team drew comparisons with other modern megafauna, such as the whale shark and the basking shark, both of which maintain slender profiles to enhance their hydrodynamic efficiency.

The heightened emphasis on hydrodynamics elucidates why certain marine creatures, including Megalodon, achieved such impressive sizes, while others, like the great white shark, could not surpass particular physical limits. This contrasts starkly with prior assumptions that larger size predominantly resulted from enhanced predatory capabilities; instead, it suggests that anatomical form is vital for the viability of large-bodied species within marine ecosystems. This newfound understanding could lead to further exploration into the behavior and success of gigantic animals across evolutionary contexts.

The collaborative effort extended beyond established researchers to include two former master’s students of Shimada, Phillip Sternes and Jake Wood. Their contributions enriched the study’s perspective and depth of understanding. Sternes, now an educator at SeaWorld San Diego, noted that the study unequivocally reinforces prior assertions regarding Megalodon’s anatomy and challenges the perception of this giant predator as merely a scaled-up version of its modern relative. Wood, who currently pursues a doctoral degree, emphasized that their innovative research approach provides compelling new insights distinct from prior studies about Megalodon.

In addition to creating a more accurate picture of size and form, the study reassesses various biological aspects, including growth patterns and life history strategies. For instance, the findings suggest that a fully grown Megalodon could have weighed around 94 tons and swum at cruising speeds comparable to modern great white sharks, around 2.1–3.5 kilometers (1.3–2.2 miles) per hour. Furthermore, evidence gleaned from the studied vertebral column infers that newborn Megalodons would have emerged live, measuring between 3.6 to 3.9 meters in length, highlighting a fascinating aspect of their reproductive biology.

Moreover, the intricate relationship between Megalodon and emerging species such as modern great white sharks raises evolutionary questions. The study posits that the ascendance of the great white shark approximately 5 million years ago could have contributed to the eventual decline of Megalodon, suggesting competitive interactions played a critical role in the extinction of this awe-inspiring apex predator. These data-driven interpretations may set the stage for future investigations into the biology of not only Megalodon but also the dynamics of prehistoric marine ecosystems.

Despite the significant advances this study has made, Shimada acknowledges the provisional nature of many interpretations, asserting that they are rooted in empirical evidence and serve as reference points for future research. Optimistically, he hopes that the discovery of a complete Megalodon skeleton may one day validate these interpretations, enriching the narrative of one of history’s most enigmatic marine megafauna and ensuring its significance within paleontological discourse.

This study, titled “Reassessment of the possible size, form, weight, cruising speed, and growth parameters of the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), and new evolutionary insights into its gigantism, life history strategies, ecology, and extinction,” is anticipated to contribute to ongoing conversations surrounding marine biology, evolution, and the rich tapestry of life that flourished long before human existence.

Subject of Research: Animals
Article Title: Reassessment of the possible size, form, weight, cruising speed, and growth parameters of the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), and new evolutionary insights into its gigantism, life history strategies, ecology, and extinction
News Publication Date: 9-Mar-2025
Web References: 10.26879/1502
References: https://doi.org/10.26879/1345
Image Credits: DePaul University/Kenshu Shimada
Keywords: Paleontology, Megalodon, Marine Biology, Evolution, Extinction, Sharks, Fossils

Tags: aquatic vertebrate gigantismcomparative analysis of shark speciesextinct marine species studiesfossil evidence of megalodoninsights from fossil discoveriesmarine predator evolutionMegalodon size and shapeOtodus megalodon researchpaleobiology of prehistoric sharkspaleontological methods advancementsshark anatomy and morphologyvertebrate biology research