Cenozoic megatooth sharks occupied extremely high trophic positions.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35731884.
- Also identified by DOI 10.1126/sciadv.abl6529 and PMC identifier 9217088.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Trophic position is a fundamental characteristic of animals, yet it is unknown in many extinct species. In this study, we ground-truth the <sup>15</sup>N/<sup>14</sup>N ratio of enameloid-bound organic matter (δ<sup>15</sup>N<sub>EB</sub>) as a trophic level proxy by comparison to dentin collagen δ<sup>15</sup>N and apply this method to the fossil record to reconstruct the trophic level of the megatooth sharks (genus <i>Otodus</i>). These sharks evolved in the Cenozoic, culminating in <i>Otodus megalodon</i>, a shark with a maximum body size of more than 15 m, which went extinct 3.5 million years ago. Very high δ<sup>15</sup>N<sub>EB</sub> values (22.9 ± 4.4‰) of <i>O. megalodon</i> from the Miocene and Pliocene show that it occupied a higher trophic level than is known for any marine species, extinct or extant. δ<sup>15</sup>N<sub>EB</sub> also indicates a dietary shift in sharks of the megatooth lineage as they evolved toward the gigantic <i>O. megalodon</i>, with the highest trophic level apparently reached earlier than peak size.