Megalodon, the gigantic prehistoric shark that first appeared about 15 million years ago and became extinct 3.6 million years ago, is an icon of the prehistoric era. Famous for its giant teeth, it was one of the largest marine carnivores ever to live. Given its considerable impact on marine ecosystems, it is still a popular research subject today. In order to better understand its biology and, thus, its behaviour, the correct reconstruction of its body shape is of vital importance. Previously, this constituted a challenge for researchers, since only teeth and vertebrae have been preserved, but no complete skeleton.
 
Previous assumptions
The fact that, like the white shark, megalodon was able to partially regulate its body temperature (“regional warm-bloodedness”) and had similarly shaped teeth, was long considered to mean that its body shape also resembled that of the modern-day white shark. Accordingly, the white shark was traditionally used as a model species for interpreting the lifestyle and shape of megalodon – an approach that has now been thrown into doubt by the latest research findings, as palaeobiologist Jürgen Kriwet from the Department of Palaeontology at the University of Vienna explains: “In the past, the shape assumed for megalodon led researchers to believe that it was a fast swimmer and resembled today’s mackerel sharks – the so-called lamnid sharks –, a family that also includes the white shark. There are, however, some weak points in this scientific reasoning.”
 
How the story continues
Based on a partially preserved vertebral column of megalodon and some modern-day lamnid specimens, the research team has now reassessed the 2D and 3D reconstruction of the prehistoric shark’s body shape. It turned out that the assumptions of previous studies were incorrect in large parts. “Using an incomplete vertebral column without additional skeletal elements such as the skull and comparing it with a CT scan of a young white shark without taking into account ontogenetic changes in order to reconstruct the megalodon’s body shape and, thus, biological aspects, is a greatly error-prone approach,” notes palaeobiologist Jürgen Kriwet. But despite their deficits, previous studies have still furnished one important pointer for megalodon’s body shape: it was elongated relative to the body of the modern white shark.
 
Reassessing body shape and lifestyle
The anatomical comparison of the vertebral columns of modern-day mackerel sharks with that of megalodon shows that the ancient giant shark was longer and slimmer. Even if its actual body shape has not been completely ascertained, the new findings are of great biological significance. “In combination, this gives us the picture of a relatively slender and elongated, regionally warm-blooded, rather slow-swimming top predator, that occupied a similar or even higher trophic position than today’s great white shark,” says palaeobiologist Patrick L. Jambura from the Department of Palaeontology at the University of Vienna. “Our study shows that a thorough analysis of all available data and a careful selection of modern-day sharks as model organisms can provide important pointers to the lifestyle and biology of extinct shark species,” adds palaeobiologist Julia Türtscher from the Department of Palaeontology at the University of Vienna.
 
Although it reigned supreme at the top of the food chain for almost 12 million years, megalodon became extinct roughly 3.6 million years ago. Its downfall may have been brought about by climatic changes, but also by today’s great white sharks – which probably reach sexual maturity more quickly. “Understanding the success, but also the extinction, of such marine predators is of great significance since it enables us to draw conclusions about the future of today’s top predators, which are indispensable for the ecological balance of the oceans,” explains palaeontologist Iris Feichtinger from the Natural History Museum Vienna.
 
Publication in Palaentologia Electronica: White shark comparison reveals a slender body for the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae)
Phillip C. Sternes, Patrick L. Jambura, Julia Türtscher, Jürgen Kriwet, Mikael Siversson, Iris Feichtinger, Gavin J. P. Naylor, Adam P. Summers, John G. Maisey, Taketeru Tomita, Joshua K. Moyer, Timothy E. Higham, João Paulo C. B. da Silva, Hugo Bornatowski, Douglas J. Long, Victor J. Perez, Alberto Collareta, Charlie Underwood, David J. Ward, Romain Vullo, Gerardo González-Barba, Harry M. Maisch IV, Michael L. Griffiths, Martin A. Becker, Jake J. Wood, Kenshu Shimada;
https://palaeo-electronica.org/content/2024/5079-megalodon-body-form

Please find press material for download under the following link:
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Iris Feichtinger
Geologisch-Paläontologische Abteilung des NHM Wien
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Prof. Dr. Jürgen Kriwet
Institut für Paläontologie, Universität Wien
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