The seismic wave motion camouflage of large carnivorous dinosaurs

Living elephants produce seismic waves during vocalizations and locomotion that are potentially detectable at large distances. In the Mesozoic world, seismic waves were probably a very relevant source of information about the behavior of large dinosaurs. In this work, we study the relationship between foot shape and the directivity pattern of seismic waves generated during locomotion. For enlarged foot morphologies (based on a morphological index) of theropod dinosaurs, there is a marked effect of seismic wave directivity at 20 m. This effect is not important in the foot morphologies of other dinosaurs, including the foot shapes of herbivores and theropods such as therizinosaurids. This directivity produces a lower intensity in the forward direction that would slightly reduce the probability of detection of an ambush predator. Even more relevant is the fact that during the approach of a predator, the intensity of seismic waves detected by potential prey remains constant in the mentioned distance range. This effect hides the predator's approach, and we call this "seismic wave camouflage". We also discuss the potential relationship of this effect with enlarged fossil footprints assigned to metatarsal support. (C) 2018 Elsevier Ltd. All rights reserved.