Name: Otodus megalodon
Name Meaning: Giant Ear-Shaped Tooth
Age: Middle Miocene to Pliocene (15.9 – 2.6 million years ago)
Size: 15 – 18 m in length approx.
Imagine, for a moment, you are a young child during the Renaissance, playing near some rocky outcrops, when you come across a huge triangular tooth, 18 cm long. Would you have any idea where it came from? Renaissance naturalists knew these stones as glossopetrae, or ‘tongue stones’, representing the remains of the tongues of humans, snakes, or even dragons. In 1667, after studying the teeth of “a huge shark” under a microscope, Nicholas Steno reported the resemblance of these teeth to glossopetrae. It wouldn’t be until 1843 that Louis Agassiz would name the owner of these amazing remains, Carcharodon megalodon, the biggest shark ever discovered. The animal was later referred to as Carcharocles megalodon but was more recently reclassified as Otodus megalodon.
Otodus megalodon, more famously known as just Megalodon, is the biggest shark ever discovered, at up to 18 m long, in a family of big sharks called Otodontidae. A recent estimate suggests that Megalodon rarely exceeded 15 m in length, compared to the 18 m estimates of the past, which is still over double the length of the modern great white shark (Carcharodon carcharias). Megalodon likely got so big due to its speciality in hunting marine mammals such as Piscobalaena nana, a small baleen whale. Like a modern great white shark which preys upon smaller seals, it has been hypothesised that Megalodon preyed upon smaller, high-calorie whales.
Megalodon ruled the seas as an apex predator for well over 10 million years, and the reasons for why it went extinct have been somewhat unclear. It was hypothesised that cooling global temperatures during the ice ages caused Megalodon’s favoured food, whales, to become more migratory, travelling to the poles where Megalodon couldn’t follow. However, more recent studies have shown that there is no correlation between mean annual temperatures and Megalodon abundance, so it is unlikely that climate change was the sole cause of their extinction. Instead, it is now believed that competition from other predators, like Livyatan, and the great white shark, along with a drop in the diversity of filter-feeding whales, like Piscobaleena, were likely what drove Megalodon to extinction.
We understand quite a bit about Megalodon and its life history, such as the fact they used nurseries where their young grew and matured, despite the lack of complete fossil skeletons. Like most sharks, Megalodon had a cartilaginous skeleton that doesn’t fossilise well. The only part of their skeleton that does fossilise well is the teeth, which are found in abundance all over the world. This is because teeth are extremely tough, so unlike cartilage, can survive long enough to be fossilised. Like many sharks today, Megalodon continually shed their teeth and grew new ones, meaning that a single shark could have produced hundreds of teeth in their life that could end up becoming fossils.
Despite misleading ‘nature documentaries’ in the past, Emma Bernard of the London Natural History Museum emphasises that Megalodon isn’t alive today in the deep oceans. Their massive bite marks would be easily noticed on its large marine prey; they wouldn’t be able to survive in colder deep waters (in which they would be more likely to remain undetected); and their infamously large teeth would likely litter the seafloor.
Although Megalodon isn’t alive today, and its fossil teeth are a relatively common find, recent news has shown that it can still stir up trouble. After Sir David Attenborough gave a Megalodon tooth, which he had found over 50 years earlier in Malta, to Prince George, there were concerns over whether it should be returned to Malta as part of its national heritage. This follows the Cultural Heritage Act 2002, according to which the removal or excavation of fossils is now expressly forbidden.
In the face of these controversies, Megalodon still remains one of the most famous prehistoric animals in popular culture, inspiring many movies with its colossal size. However, its demise may go somewhat towards the maxim that bigger isn’t better.
 Otodus megalodon hunting. Artwork by Alberto Gennari.
 A representation of changes in tooth morphology and an increase in size within the megatooth lineage. Taken from Pimiento & Balk (2015).
Information References and Further Sources
 Agassiz, L. (1843). Recherches sur les Poissons Fossiles [Research on the fossil fishes] (in French). Neuchatel: Petitpierre. pp. 41. Accessed 7th October 2020. Click Here.
 Bouetel, V., and de Muizon, C., (2006). ‘The anatomy and relationships of Piscobalaena nana (Cetacea, Mysticeti), a Cetotheriidae s.s. from the early Pliocene of Peru’, Geodiversitas, 28 (2), pp. 319-395. Accessed 7th October 2020. Click Here.
 Collareta, A., Lambert, O., Landini, W., Di Celma, C., Malinverno, E., Varas-Malca, R., Urbina, M., and Bianucci, G. (2017). ‘Did the giant extinct shark Carcharocles megalodon target small prey? Bite marks on marine mammal remains from the late Miocene of Peru’, Palaeogeography, Palaeoclimatology, Palaeoecology, 469, pp. 84-91. Accessed 7th October 2020. Click Here.
 Cooper, J. A., Pimiento, C., Ferrón, H. G., and Benton, M. J. (2020). ‘Body dimensions of the extinct giant shark Otodus megalodon: a 2D reconstruction’, Scientific Reports, 10 (14596). Accessed 7th October 2020. Click Here.
 Davies, C. (2020). ‘Questions raised in Malta over Prince George’s shark tooth gift from David Attenborough’, The Guardian. 28th September 2020. Accessed 7th October 2020. Click Here.
 Davis, J. (Unknown). ‘Megalodon: the truth about the largest shark that ever lived’, Natural History Museum. Accessed 7th October 2020. Click Here.
 Pimiento, C., and Balk, M. A. (2015). ‘Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators’, Paleobiology, 41 (3), pp. 479-490. Accessed 7th October 2020. Click Here.
 Pimiento, C., MacFadden, B. J., Clements, C. F., Varela, S., Jaramillo, C., Velez-Juarbe, J., and Silliman, B. R. (2016). ‘Geographical distribution patterns of Carcharocles megalodon over time reveal clues about extinction mechanisms’, Journal of Biogeography, 43 (8), pp. 1645-1655. Accessed 7th October 2020. Click Here.
 Shimada, K. (2019). ‘The size of the megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), revisited’, Historical Biology, pp. 1-8. Accessed 7th October 2020. Click Here.
 Haven, K. (2007). 100 Greatest Science Discoveries of All Time. Libraries Unlimited Inc. pp. 25-26.
 Hsu, K-T. (2009). ‘The Path to Steno’s synthesis on the animal origin of glossopetrae’, in Rosenberg, G. D. The Revolution in Geology from the Renaissance to the Enlightenment. Geological Society of America. pp. 94-106. Accessed 7th October 2020. Click Here.