Kast Emma R, Griffiths Michael L, Kim Sora L, Rao Zixuan C, Shimada Kenshu, Becker Martin A, Maisch Harry M, Eagle Robert A, Clarke Chelesia A, Neumann Allison N, Karnes Molly E, Lüdecke Tina, Leichliter Jennifer N, Martínez-García Alfredo, Akhtar Alliya A, Wang Xingchen T, Haug Gerald H, Sigman Daniel M
Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.
Department of Earth Sciences, University of Cambridge, Cambridge, CB23EQ, UK.
Sci Adv. 2022 Jun 24;8(25):eabl6529. doi: 10.1126/sciadv.abl6529. Epub 2022 Jun 22.
Trophic position is a fundamental characteristic of animals, yet it is unknown in many extinct species. In this study, we ground-truth the N/N ratio of enameloid-bound organic matter (δN) as a trophic level proxy by comparison to dentin collagen δN and apply this method to the fossil record to reconstruct the trophic level of the megatooth sharks (genus ). These sharks evolved in the Cenozoic, culminating in , a shark with a maximum body size of more than 15 m, which went extinct 3.5 million years ago. Very high δN values (22.9 ± 4.4‰) of from the Miocene and Pliocene show that it occupied a higher trophic level than is known for any marine species, extinct or extant. δN also indicates a dietary shift in sharks of the megatooth lineage as they evolved toward the gigantic , with the highest trophic level apparently reached earlier than peak size.
营养级是动物的一个基本特征，但在许多已灭绝物种中尚不清楚。在本研究中，我们通过与牙本质胶原蛋白δN进行比较，将牙釉质结合有机物的N/N比（δN）作为营养级代理进行实地验证，并将此方法应用于化石记录，以重建巨齿鲨（属）的营养级。这些鲨鱼在新生代进化，在[具体物种名称]达到顶峰，这是一种最大体长超过15米的鲨鱼，于350万年前灭绝。中新世和上新世[具体物种名称]的δN值非常高（22.9±4.4‰），表明它占据了比任何已知的海洋物种（已灭绝或现存）都更高的营养级。δN还表明，随着巨齿鲨谱系的鲨鱼进化为巨大的[具体物种名称]，它们的饮食发生了变化，最高营养级显然比体型峰值出现得更早。
