Before revision: While terrestrial tetrapods are theorised to have a single origin, arthropods and their relatives are thought to have independently evolved walking several times, specifically in insects , myriapods, chelicerates, tardigrades, onychophorans, and crustaceans.
After revision: While terrestrial tetrapods are theorised to have a single origin, arthropods and their relatives are thought to have independently evolved walking several times, specifically in hexapods , myriapods, chelicerates, tardigrades, onychophorans, and crustaceans.