Evolutionary history
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Apex predators are thought to have existed since at least the Cambrian period, around 500 million years ago. Extinct species cannot be directly determined to be apex predators as their behavior cannot be observed, and clues to ecological relationships, such as bite marks on bones or shells, do not form a complete picture. However, indirect evidence such as the absence of any discernible predator in an environment is suggestive. Anomalocaris was an aquatic apex predator, in the Cambrian. Its mouthparts are clearly predatory, and there were no larger animals in the seas at that time.[32]
Carnivorous theropod dinosaurs including Allosaurus[33] and Tyrannosaurus[34] are theorized to have been apex predators, based on their size, morphology, and dietary needs.
A Permian shark, Triodus sessilis, was discovered containing two amphibians (Archegosaurus decheni and Cheliderpeton latirostre), one of which had consumed a fish, Acanthodes bronni, showing that the shark had lived at a trophic level of at least 4.[c][35]
Among more recent fossils, the saber-tooth cats, like Smilodon, are considered to have been apex predators in the Cenozoic.[36]