Waptia revisited: Intimations of behaviors

•Morphology, sensory organization, and the visual system of the Mid-Cambrian species Waptia fieldensis is interpreted in the context of plausible behaviors.•Specific morphological features are indicative of a mandibulate euarthropod with a few attributes suggestive of a pancrustacean affinity.•Traces of cerebral nervous system and peripheral nerves support the presence of a tripartite brain and support the contention that the second antenna pair has undergone an evolved loss.

The middle Cambrian taxon Waptia fieldensis offers insights into early evolution of sensory arrangements that may have supported a range of actions such as exploratory behavior, burrowing, scavenging, swimming, and escape, amongst others. Less elaborate than many modern pancrustaceans, specific features of Waptia that suggest a possible association with the pancrustacean evolutionary trajectory, include mandibulate mouthparts, a single pair of antennae, reflective triplets on the head comparable to ocelli, and traces of brain and optic lobes that conform to the pancrustacean ground pattern. This account revisits an earlier description of Waptia to further interpret the distribution of its overall morphology and receptor arrangements in the context of plausible behavioral repertoires.