For thousands and thousands of years, megalodon sharks have been prime ocean predators — after which got here the nice whites. New analyses of tooth trace that competitors for meals from nice white sharks might have helped give the megatoothed giants an additional shove towards extinction.
Scientists reconstructed shark feeding habits by analyzing zinc within the tooth of 20 residing shark species and 13 extinct species, together with megalodons (Otodus megalodon). Megalodons and nice whites occupied the same ecological area of interest, devouring marine mammals equivalent to whales and seals, the researchers report May 31 in Nature Communications.
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O. megalodon was one of many largest carnivores ever to reside, rising to at the least 14 meters lengthy (SN: 1/12/21). This big started menacing the oceans round 23 million years in the past. When — and why — it went extinct isn’t clear. The species might have lingered till about 2.6 million years in the past. Or it might have vanished as early as 3.5 million years in the past, proper across the time that the nice white shark Carcharodon carcharias appeared.
To determine if the 2 sharks dined on comparable meals, the researchers turned to zinc, which has two primary types: zinc-66 and zinc-64. The relative abundances of these isotopes, preserved in tooth enamel, can point out an animal’s place in a meals internet. Plants — and plant eaters — are comparatively excessive in zinc-66. Higher up the meals chain, that 66-to-64 ratio decreases.
The analyses revealed that when and the place O. megalodon and C. carcharias overlapped, the sharks had comparable ratios. That discovering means that their diets overlapped too, say geoscientist Jeremy McCormack of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues.
Still, that the sharks consumed comparable prey isn’t proof they have been in competitors, the researchers say. And there are a lot of elements which will have helped drive megalodons to extinction (SN: 8/10/18). Those elements embrace ocean circulation modifications, collapsing prey populations and competitors for meals with different ocean creatures, like orcas.