Evidence Supporting Predation of 4-m Marine Reptile by Triassic Megapredator.

Da-Yong Jiang,Xue Wang,Cheng Ji,Ryosuke Motani,Zhi-Guang Li,Hao Lu,Min Zhou,Olivier Rieppel,Andrea Tintori

doi:10.1016/j.isci.2020.101347

Abstract

SummaryAir-breathing marine predators have been essential components of the marine ecosystem since the Triassic. Many of them are considered the apex predators but without direct evidence—dietary inferences are usually based on circumstantial evidence, such as tooth shape. Here we report a fossil that likely represents the oldest evidence for predation on megafauna, i.e., animals equal to or larger than humans, by marine tetrapods—a thalattosaur (∼4 m in total length) in the stomach of a Middle Triassic ichthyosaur (∼5 m). The predator has grasping teeth yet swallowed the body trunk of the prey in one to several pieces. There were many more Mesozoic marine reptiles with similar grasping teeth, so megafaunal predation was likely more widespread than presently conceived. Megafaunal predation probably started nearly simultaneously in multiple lineages of marine reptiles in the Illyrian (about 242–243 million years ago).

Highlights

Land vertebrates started recolonizing the sea after the end-Permian mass extinction and diversified into many ecomorphs including apex predators (Kelley and Pyenson, 2015; Motani, 2009; Vermeij and Motani, 2018)
The largest Mesozoic marine reptile, belonging to ichthyosaurs, was edentulous (Nicholls and Manabe, 2004), suggesting it did not feed on large bony prey
Bromalite Features The main specimen studied (XNGM-WS-50-R4) is of an ichthyosaur identified as Guizhouichthyosaurus (Methods), containing a dense concentration of many bones inside the ribs and gastralia in the abdominal region (Figure 1)

Summary

Introduction

Land vertebrates started recolonizing the sea after the end-Permian mass extinction and diversified into many ecomorphs including apex predators (Kelley and Pyenson, 2015; Motani, 2009; Vermeij and Motani, 2018) Such predators are found among cetaceans and pinnipeds in the modern ecosystem but belonged to marine reptiles, such as plesiosaurs, mosasaurs, and ichthyosaurs, in the Mesozoic (Massare, 1987). There are larger whales, such as baleen whales (up to about 30 m), sperm whale (up to about 18 m), and beaked whales (up to about 12 m) (Jefferson et al, 1993), but they are not apex predators

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Discussion

Conclusion