You'll note that the original concept of a prehistoric Lost World-type setting had been jettisoned in favor of the more-or-less standard African jungle with evil and/or idiot White hunters creating trouble.
Presumably, this was done to facilitate a potential movie serial deal like the one made for Cave Girl's companion strip Thun'da. which Fox and Powell were also handling since it's creator and original artist, Frank Frazetta, had quit when the series' editorial direction was abruptly changed! (Following standard editorial practice of the period, he had not retained copyright or editorial control of the character.)
The occasional lost ancient city or lone prehistoric beast would still pop up, but the emphasis was on a present-day "darkest Africa" motif which would remain both in her Thun'da backup tales and her own short-lived title.

The very first Cave Girl story (but not her origin) from Thun'da #2, guest-starring Thun'da himself, along with his "mate", Pha!
Art by "good girl" artist Bob Powell, who took over on Thun'da from the legendary Frank Frazetta!
Cave Girl continued as a back-up in the remaining four issues of Thun'da, and as the lead in four issues of her own title (with a Thun'da strip as a back-up!).
Despite the overlapping of the strips in each other's books, the characters never guest-starred in each other's strips again.