Pygmaclypeatus daziensis was a small early trilobitomorph arthropod that lived during the Cambrian, about 518 million years ago, in what is now southwestern China.
It had a wide flat carapace, about 14mm long (~0.5″), with a single pair of antennae, fourteen pairs of limbs, and a short segmented “tail”.
It also had an unusual arrangement of four eyes — one pair of fixed-in-place trilobite-like eyes on top of its headshield, and a second pair of crustacean-like mobile stalked eyes on the underside. Other four-eyed Cambrian arthropods are known, but Pygmaclypeatus is currently unique for having two completely different compound eye systems.
Its well-developed limbs with paddle-like branches indicate it could swim well, and probably also burrow into soft seafloor sediment. Its upper eyes seem to have been adapted to sensing motion in dim daylight conditions, suggesting they were used to keep a lookout for predators in shallow murky water. Its lower eyes were more sensitive, and may have been used to locate food items such as smaller soft-bodied invertebrates or organic detritus on the seafloor.
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