Fossil Shark Tooth - Carcharodon megalodon.
Image: Rodney Start
Source: Museum Victoria
Question: Can you tell me about this giant tooth I found that looks like a shark tooth? Is it a fossil? It looks pretty new but is huge and I can’t imagine what shark it would have come from!
Answer: This huge tooth is indeed a fossil! It comes from an extinct shark called Carcharocles megalodon, which lived approximately 20 to 3 million years ago during the Miocene and Pliocene epochs. The word megalodon comes from Ancient Greek words meaning ‘big’ and ‘tooth’ and the shark is known by various names, including the Giant ‘Mega-tooth’ Shark, Giant-toothed Shark, the Giant White Shark and the Fossil Great White Shark.
Megalodon was distributed throughout the oceans of the world, with fossil remains found from Belgium to California; from Morocco to Peru. They are also found at a number of sites in Australia and we have an 11cm Megalodon tooth from Beaumaris in the Discovery Centre. Only the teeth, vertebrae and fin bones of the Megalodon have been found because shark skeletons are mainly made of cartilage, which decomposes too quickly for it to become fossilised.
Nevertheless, we still can find out lots of information about these ancient sharks from these fossil remains. We can compare them to modern sharks and infer information from similarities of their skeletal material, including their bone structure, development, hunting and eating habits.
The Megalodon probably looked similar to the modern Great White Shark (White Pointer) but was much bigger. Its fossils indicate that it could have measured up to 15m in length and weighed up to 50 tonnes (50,000kg). The teeth of this giant can be up to 18cm long. Reconstructions have been made of their jaws based on the shape of the teeth and suggest that the gape was up to 2m, enough for a human to stand up in its mouth! The size, shape and serrated edges of Megalodon teeth are similar to the Great White and it probably ate whales, seals, turtles and large fish. With its enormous size Megalodon would have needed a large amount of food, perhaps up to 1100kg of meat every day.
The Carcharocles megalodon used to be known as Carcharodon megalodon. Scientists had for many years thought the modern great white (Carcharadon carcharias) was an ancestor of the Megalodon and, therefore, were classed in same genus (Carcharodon). But recent work by palaeontologists has now turned this idea around, suggesting that the Megalodon and Great White are descended from different lines.
Why did these giants die out? The increasingly cold climate in the late Pliocene (which heralded the beginning of the great Ice Age in the Pleistocene) almost certainly was responsible for the extinction of these creatures. There are many factors that may have affected them but it is possible that they may not have been very well adapted to the cooling sea temperatures, or that their prey moves to waters too cold for them to follow to. Another more speculative idea is that Megalodon was out-competed by Killer Whales, which seem to have evolved towards the end of Megalodon’s reign.
Rumours still abound among fisherman about giant sharks bigger than normal Great Whites. This has led to stories that these creatures may still be living in the deep sea somewhere. But scientists have not found any Megalodon teeth in recent marine deposits and the rumours are without basis. Like many of the giant animals that roamed the earth in the era, these marine creatures of the Miocene and Pliocene can only be seen in paintings and re-creations.