Figure 6 — Schematic tree depicting the gradual establishment of the velvet worm body plan. Stacked claws evolved before the last common ancestor of Hallucigenia and velvet worms (circled); toothed jaws and slime glands arose later on the lineage to modern velvet worms (dark green, top). Hallucigenia occupies a side-branch whose Cambrian diversity was much greater than that of the lineage leading to modern velvet worms.