Onychoporans (also known as velvet worms) share certain characters with arthropods, but are lacking a hard exoskeleton or jointed legs. Onychophorans are probably closely related to arthropods and branched off the tree just before a fully hardened exoskeleton and jointed legs evolved.

Onychophoran photo provided by Dr. Lynn Kimsey and the Bohart Museum of Entomology, University of California Davis