For more than 100 years, most pterosaur workers have accepted the traditional reconstruction of the pteroid, articulated in the fovea of the preaxial carpal and directed medially along the anterior margin of a small propatagium in order to control it. A few workers have rejected the traditional reconstruction and advocated an alternative reconstruction with the pteroid directed anteriorly and controlling a large propatagium extending laterally past the wrist. Articulated specimens of a wide range of pterosaurs preserve a sesamoid associated with the tendon of M. flexorcarpi ulnaris in the fovea of the preaxial carpal. No specimen preserves the pteroid articulated in the fovea, and because the sesamoid articulated there, the pteroid could not. Therefore, both the traditional and alternative reconstructions, which are based on the assumption that the pteroid articulated in the fovea, are falsified. The preaxial carpal acted as a strut to increase the leverage of M. flexor carpi ulnaris for wrist extension. The pteroid articulated with the side of the carpal, was directed medially toward the shoulder, and could be extended and depressed to control the propatagium.