Episode five in screening order but episode three in production order (after Condemned Of Space and Hunter's Moon). The Robinson's new lost planet has a trouble-making volcano.
The Space Primevals is a good looking hour that sometimes leaves that boring sound stage for once and gives us some striking outdoor images of the full scale space pod and great sound stage dramatics from the cave men-like tribe on the planet.
The Lost World (1960) lizard drops in for a second or two but we will try to forget about that. If you take away Don, Smith and The Robot, this tone/look of this hour resembles Land Of The Giants and Voyage to the Bottom of the Sea. In fact, at about this time on another Fox sound stage, Voyage/Sea was doing a volcano episode called Fires Of Death. Irwin was at work here.
Added note: Yes, the head cave-man is often standing next to props used as The Time Tunnel core.
Great episode!