Thursday, March 6, 2008

Shark Chronicles 004 - Megalodon: the Prehistoric Predator

The Megalodon, Meg, (Carcharodon megalodon), is a prehistoric shark, amongst the largest and most formidable of the extinct marine predators. This fearsome fish first roamed the world’s oceans 16 million years ago in tandem with a proliferation of marine mammals, species of primitive whale forms and dolphins on which the Megalodon might have preyed. The Megalodon may have fulfilled an ambitious and unique ecological niche but, ultimately, did not withstand the test of evolutionary time. Most research suggests that the Megalodon’s extinction, about 1.5 million years ago, was linked to the extinction of its prey, a group of slow swimming, baleen whales called Catotheriids. However, the Megalodon’s legacy persists in the form of its smaller but none the less charismatic cousin, the great white shark (“Great White”).

Recently, SAMPLA hosted Creative Difference, the film company producing National Geographic’s PREHISTORIC PREDATORS series. They required the expertise of SAMPLA to assess the biology and behaviour of the Megalodon in context of the Great White. Do our studies of the Great White give us insight into the life of the Megaladon over and above what we know of the Megalodon from the fossil record? In attempt to answer a minuscule aspect of this question, SAMPLA turned to research it had done on the Great White using the bite force meter, a device that measures the voluntary bite power of an animal. All we have from Megalodon is fossilized teeth, which limits the investigation somewhat!

The Megaladon’s teeth show remarkable similarities to adult Great Whites. Both have large and triangular teeth and, more importantly, both are serrated. These serrations serve to remove chunks of a captured prey by sawing. Serrations are a useful adaptation if you capture large prey, marine mammals for example, that can not be ingested whole. Thus as the Great White saws chunks of blubber from a seal, so it is likely the Megalodon sawed blubber from its prey too (the serrated teeth adaptation suggesting that not all its prey could be ingested whole). A Megalodon is estimated to grow to 60ft (18 m) compared to a 20 ft (6 m) for a Great White. Therefore, if one ‘scaled up’ for length, Megalodon potentially had a bite force of nine times that of a Great White. If you have been privileged enough to see the impact of a Great White’s initial ‘crippling’ bite on a seal and its subsequent worrying of the carcass, to imagine that in the context of a Megalodon and its prey is awe inspiring.

However, all this is conjecture – long on speculation and short on information. To compare two great marine predators with such little information is nothing more than indulgence, but thrilling indulgence! All we have is a set of Meg’s remarkable teeth from the fossil strata, and the bones of other animals (potential prey) that occurred concurrently.

RYAN & TOBY

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