Was this bizarre Cambrian predator actually a fearsome hunter or a gentle scavenger?

Nature · Published 3 October 2026 Swipe more like this →

In short: Anomalocaris was once considered the apex predator of the Cambrian seas, a metre-long terror with spiked arms and compound eyes. Yet, recent debates over its soft mouthparts and lack of wear on its teeth suggest this ancient creature might have been far less aggressive than its terrifying reputation implies.

Living over half a billion years ago, Anomalocaris has long been defined by its strange, piecemeal discovery. In 1892, Joseph Whiteaves identified its grasping arms as a shrimp-like tail, while Charles Walcott later misidentified its ring-shaped mouth as a jellyfish. It was not until 1981 that Harry Whittington and Derek Briggs successfully reassembled these disparate fossils, revealing the true, bizarre anatomy of a creature that once dominated primordial waters.

The predator's status as a fearsome hunter is largely based on its sophisticated anatomy. It possessed undulating side flaps, a fan-shaped tail, and large stalked eyes. Research by John Paterson on fossils from South Australia’s Emu Bay Shale suggests these eyes were incredibly advanced, containing at least 16,700 lenses each. This level of visual acuity, potentially providing 360-degree vision, would have been exceptional for the Cambrian period, rivalling the capabilities of modern predatory dragonflies.

However, the narrative of a relentless trilobite-crusher is heavily contested. While some point to bite marks on trilobites as evidence of its hunting prowess, researchers like Whitey Hagadorn argue that the creature's mouthparts were too soft to penetrate thick armor. This has led to the theory that Anomalocaris may have focused on soft-bodied prey instead. Even the attribution of the Emu Bay eyes to the genus remains a subject of scientific disagreement, with experts like Jan Bergstrom questioning the evidence. Ultimately, 515 million years after its extinction, the true nature of this ancient arthropod remains a subject of intense paleontological debate.

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