Shark tooth analysis suggests that the two ocean predators battled for food.
|Megalodons may have been driven to extinction by great white sharks.|
Megalodon sharks were the leading ocean predators for millions of years until the great whites arrived. New tooth analysis suggests that competition for food from great white sharks may have contributed to the megatoothed giants' extinction.
Scientists analyzed zinc in the teeth of 20 contemporary shark species and 13 extinct shark species, including megalodons, to reconstruct shark feeding habits (Otodus megalodon). The researchers published in Nature Communications on May 31 that megalodons and great white sharks shared an ecological niche, consuming marine mammals like whales and seals.
O. megalodon was one of the world's largest carnivores, reaching a length of at least 14 meters (SN: 1/12/21). Around 23 million years ago, this colossus began to threaten the oceans. It's unclear when — or why — it went extinct. It's possible that the species survived until roughly 2.6 million years ago. It could have died out as recently as 3.5 million years ago, about the same time as the great white shark Carcharodon carcharias.
The researchers looked at zinc, which comes in two forms: zinc-66 and zinc-64, to see if the two sharks ate identical foods. The relative abundances of those isotopes, which are stored in tooth enamel, can be used to determine an animal's place in the food chain. Plants — and plant eaters — have a high zinc-66 content. The 66-to-64 ratio decreases as you move up the food chain.
When and where O. megalodon and C. carcharias overlapped, the sharks had identical ratios, according to the findings. According to geoscientist Jeremy McCormack of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues, this finding shows that their diets also overlapped.
The fact that the sharks ate identical species doesn't mean they were in competition, according to the researchers. Many reasons may have contributed to the extinction of megalodons (SN: 8/10/18). Ocean circulation changes, collapsing prey populations, and competition for food with other ocean species, such as orcas, are among these factors.
Zinc isotopes reflect the trophic status of Otodus megalodon and great white sharks over time, according to J. McCormack et al. Nature Communications is a journal that publishes scientific papers. DOI: 10.1038/s41467-022-30528-9. Published online May 31, 2022.
The Early Pliocene extinction of the mega-toothed shark Otodus megalodon: a view from the eastern North Pacific, R. Boessenecker et al. PeerJ. DOI: 10.7717/peerj.6088. Published online February 13, 2019.