Megatooth sharks, together with megalodon, appear to have had the best place in meals webs ever occupied by marine predators
22 June 2022
Megalodon and different megatooth sharks could have eaten different predators – and one another – that means they occupied an unusually excessive place within the meals internet.
“It is extremely doubtless that megatooth sharks have been at a better trophic degree than some other marine predator,” says Zixuan Rao at Princeton University.
Rao and her colleagues made the invention by analysing nitrogen isotopes in shark tooth. There are two pure steady isotopes of nitrogen – nitrogen-15 and nitrogen-14 – each of that are present in animal tissue. Nonetheless, as a result of nitrogen-14 is preferentially excreted from dwelling organisms, animal tissue is usually richer in nitrogen-15 than it will in any other case be.
Because of this when a predator eats an animal, the flesh it consumes is richer in nitrogen-15. This richer nitrogen-15 sign is integrated into the predator’s personal flesh and turns into additional enriched because the predator additionally preferentially excretes nitrogen-14. If that predator is finally eaten, the second predator will incorporate a good richer nitrogen-15 sign into its tissues. As a result of this course of continues up meals chains, researchers can use the ratio of nitrogen-15 to nitrogen-14 in fossils to estimate how excessive up a meals internet an historic animal would have been.
Rao and her colleagues analysed nitrogen ratios in a tooth materials known as enameloid extracted from 5 extinct species of megatooth sharks. These species ranged in measurement from the three.5-metre-long Otodus auriculatus to the 15-metre-long Otodus megalodon – identified to many individuals merely as megalodon.
The researchers additionally measured the nitrogen isotope ratio in samples from current marine mammals comparable to dolphins, seals, walruses and polar bears in addition to from trendy sharks, together with the nice white.
It was the megatooth sharks that had the best nitrogen ratios – greater than any in dwelling marine predators. “We’ve by no means seen nitrogen ratio values this excessive till this challenge. We anticipated excessive values, however not this excessive,” says Rao.
The outcomes counsel not solely that megatooth sharks have been on the prime of meals webs, however that they ate different predators close to the highest of the meals internet too.
Precisely which predators the sharks ate isn’t utterly clear. The nitrogen isotope ratios in current marine mammals weren’t excessive sufficient to account for the unusually excessive nitrogen-15 ranges discovered within the megatooth fossils. It could be best to clarify the sign if megatooth sharks ate different, smaller megatooth sharks.
The outcomes additionally indicated that megatooth sharks made this shift to consuming different predators early of their evolution, once they have been comparatively small animals measuring about 3.5 metres in size.
“That is actually attention-grabbing,” says Rao. “It suggests the large measurement of the most important megatooth sharks weren’t obligatory for them to achieve the highest of the meals internet.”
Understanding the evolution and behavior of megatooth sharks will help us to grasp how previous local weather occasions impacted the marine ecosystems they lived in, says Rao. “Trying on the previous is the important thing to the long run, if we will perceive how the local weather impacted ecosystems prior to now, it could assist information us to guard life sooner or later.”
“Earlier research have recommended that megalodon occupied a better place within the meals internet than the nice white shark. This examine higher helps this speculation utilizing a a lot bigger pattern measurement and utilizing cutting-edge methodologies,” says Catalina Pimiento Hernandez at Swansea College within the UK.
Journal reference: Science Advances, DOI: 10.1126/sciadv.abl6529
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