With today’s launch of the film The Meg, Curator of Vertebrates Alan Tennyson looks at what we know about the monster that grew to 18 metres and lived in New Zealand’s waters – the megalodon ‘big tooth’ shark (Carcharocles megalodon).
In the spotlight: The Meg
The Meg, filmed in New Zealand and co-starring kiwi actors Cliff Curtis and Sophia Cai, follows a group of scientists who must stop a 23-metre long megalodon shark from terrorising a beach – sound familiar?
Many palaeontologists are enthusiastically welcoming the promotion of an extinct species in popular culture, even if the tale told in The Meg is pure fiction…
Are megalodon extinct?
Yes. They lived approximately 23 to 2.6 million years ago, so are long extinct.
How big was a megalodon?
Megalodon (meaning ‘big tooth’) was truly an enormous creature – easily the largest shark known to have existed. It’s thought they mainly ate whales, seals, and giant turtles.
Teeth have been found as large as 18cm tall, and it’s estimated megalodon could grow to a length of 18 metres. In comparison, the maximum body length recorded for the living great white shark (Carcharodon carcharias) is 6.1 metres.
Megalodon teeth in New Zealand
The cartilaginous make-up of the skeletons of sharks means that their fossil record is dominated by preserved teeth and occasional vertebrae.
We have firm evidence of the species in New Zealand as fossil teeth have been found in widespread sites in both the North and South Island.
The largest locally found tooth was collected at Waimumu in Southland and has a crown height of 12cm.
At least 20 fossilised megalodon teeth have been found in New Zealand, and their age covers most of megalodon’s 20-million-year reign over the seas.
Such teeth are rare, with only a single New Zealand specimen preserved in Te Papa’s collections (although specimens are common in some parts of the world and we also have teeth from Europe, North America, and Fiji).
Why megalodon became extinct
Why megalodon became extinct is not entirely clear but it coincides with a major global cooling event.
Megalodon preferred warmer waters, so oceanic cooling probably reduced its habitat.
This change was coupled with a major drop in sea levels as water became locked up in polar ice caps.
This greatly reduced the amount of shallow seas, which undoubtedly changed marine productivity and altered the evolution and habits of megalodon’s prey.
For example, baleen whales became enormous and shifted their distribution more towards the cool polar regions.
Competition with whale-eating cetaceans, such as Livyatan (a relative of the sperm whale with 36cm long teeth) and ancient killer whales (Orcinus citoniensis), and the (not particularly closely related) great white shark may also have contributed to megalodon’s extinction.