How Great White sharks killed off Megalodons, the biggest sharks to ever live

By Mark Waghorn via SWNS

Megalodon - the biggest shark that ever lived - was killed off by the Great White, according to new research.

The huge and powerful sea monster was outcompeted for resources by its smaller and nimbler rival, say scientists.

A study of fossilized teeth shows they chased the same animals - including whales, dolphins and porpoises.

Co-author Professor Kenshu Shimada, of DePaul University, Chicago, said: "These results likely imply at least some overlap in prey hunted by both shark species."

Analysis of zinc levels found they were at the top of the food chain - meaning nothing ate them.

An international team generated a database of values across 20 living and prehistoric shark species ranging from aquarium and wild individuals - to Megalodon.

Co-author Prof Michael Griffiths, of William Paterson University, New Jersey, said: "Our results show both megalodon and its ancestor were indeed apex predators - feeding high up their respective food chains.

"But what was truly remarkable is zinc isotope values from Early Pliocene shark teeth from North Carolina suggest largely overlapping trophic levels of early great white sharks with the much larger megalodon."

Megalodon was three-and-a-half times bigger than the Great White shark - reaching 65ft in length and weighing more than 50 tons.

Its serrated seven-inch fangs and the odd vertebrae are all that remain. A shark's skeleton is made of cartilage - which rarely survives fossilization.

The marine monster dominated the oceans between 23 million and 3.6 million years ago. Its sudden extinction has puzzled evolutionary experts for decades.

Megalodon was already six and a half feet at birth - dwarfing most humans. Offspring would have been particularly vulnerable to starvation.

Zinc in tooth enameloid - the highly mineralized portion - revealed the degree of animal matter consumption.

Results were as reliable as a more established nitrogen examination of collagen - the organic tissue in dentine.

Explained lead author Dr. Jeremy McCormack, of Goethe-University Frankfurt: "On the timescales, we investigate collagen is not preserved, and traditional nitrogen isotope analysis is therefore not possible."

Megalodon translates as 'large tooth'. They have been described as the 'ultimate cutting tools', broad and triangular - and as big as a man's hand.

The behemoth needed to eat a lot of big prey to survive including whales, large fish - and probably other sharks.

Added co-author Prof Thomas Tutken, of Johannes Gutenberg University, Mainz: "Here we demonstrate, for the first time, that diet-related zinc isotope signatures are preserved in the highly mineralized enameloid crown of fossil shark teeth."

The study in Nature Communications compared zinc levels in numerous extinct shark species from Megalodon's era with those of modern counterparts.

They also looked at ratios in Megalodon teeth and its ancestors as well as today's Great White sharks to shed light on their impact on past ecosystems - and each other.

Co-author Prof Sora Kim, of the University of California Merced, said: "We noticed a coherence of zinc isotope signals in fossil and modern analog taxa, which boosts our confidence in the method and suggests there may be minimal differences in zinc isotope values at the base of marine food webs, a confounding factor for nitrogen isotope studies."

It has been suggested Megalodon could still be alive - the premise for the 2018 Hollywood blockbuster The Meg starring action man Jason Statham.

Prof Shimada says that is impossible. As a warm-water species, it would not be able to survive in the cold waters of the deep - the only chance of going unnoticed.

He said: "While additional research is needed, our results appear to support the possibility for the dietary competition of Megalodon with Early Pliocene great white sharks."

New isotope methods such as zinc are promising tools to investigate diet, ecology, and evolution in other fossil marine vertebrates - providing a unique window into the past.

Dr. McCormack added: "Our research illustrates the feasibility of using zinc isotopes to investigate the diet and ecology of extinct animals over millions of years, a method that can also be applied to other groups of fossil animals - including our own ancestors."