The invention of fast-start predation: hydrodynamics of the predator-prey interaction in Triassic saurichthyids (Actinopterygii, ‘Palaeopterygii’)

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Ilja Kogan


The essentially Triassic Saurichthyidae are the earliest known ray-finned fishes characterized by elongate, slender bodies; posteriorly situated median fins; symmetrical tails; and elongate, pointed heads with long jaws bearing a typical predatory dentition. In recent fishes, this morphology is usually associated with a fast-start predatory lifestyle. Finds of fossil saurichthyids with preserved prey items document piscivory at least in the larger forms. Anatomical studies reveal that saurichthyids possessed large orbits and optic tecta, indicating an elaborate sense of vision crucial to perform target-oriented predatory strikes. Their locomotor system was optimized for acceleration. Hydrodynamic modeling shows that a moving Saurichthys caused only little disturbance to the surrounding water, preventing prey fishes from detecting the approaching predator by their lateral line system.

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