Time Pockets in Tarzan's Africa?

 There are two Russ Manning story arcs in the Sunday strips that feature prehistoric creatures that take place in neither Pal-ul-don nor Pellucidar. 

  One has a villainous British officer kidnap Jane and retreat to a remote marshland with stifling heat far from any outpost or native village, thinking Tarzan will never find them. Jane and her captors are astonished to encounter a living brontosaurus, and then a mosasaur!

   Jane has no idea what the dinosaurs are doing in this part of Africa, far from the lost land of Pal-ul-don!

  The tylosaurus, crazed with hunger attacks the boat, devours several men, and Jane's captors are about to feed her to the beast in order to save themselves, when Tarzan shows up!

The mystery of the dinosaurs' presence, however, is never resolved. 

We just go into another story arc wherein Korak visits a lost civilization of kraken-worshipers, and another beautiful doomed female. Korak seems to be cursed with bringing doom on every girl he encounters, but that's a whole other topic. 

What are dinosaurs doing in Tarzan's Africa far from any lost world? 

Manning already established that Pal-ul-don (or at least his take on it in this timeline), exists in a sort of "time bubble" that allowed the prehistoric races and fauna to survive. Tarzan journeys back in time, perhaps to the mid-Cenozoic, when possibly a land-bridge or connecting continent (I've speculated), existed between Africa and South America. 

Later on, Manning suggests that other such time-bubbles exists, as the time when he, Jane, Korak and some friends attempt to exit Pal-ul-don on a sail-barge over what looks like part of the Sahara (it doesn't appear to be that great thorn desert). When they become separated in a sand storm, Tarzan stumbles across a war party of ancient Egyptian solider, as realizes that "the jungle is not the only place that harbors doorways through time". Afterward, of course, the story of the Stone Pharoah unfolds.

The other Manning tale to feature prehistoric beasts is the "Mammoth Amazons," in which Korak encounters a civilization of amazon warrior women who ride wooly mammoths. How did the giant beasts get there, mammoths being native to Eurasia, never Africa (Though Korak did encounter a mammoth, which he named Trompor,  once before in the Gold-Key comics, high in Pal-ul-don's mountain ranges, and also drawn by Manning.)

By the way, Korak, mammoths ARE elephants, just not like the ones native to Africa. 

Perhaps then, this is the explanation of why so many lost cities and realms exist in ERB's Africa. It was perhaps Manning's way of making it seem more credible that so many lost civilizations and a valley full of prehistoric men and beasts could remain undiscovered in the modern world.

What what is the reason for this? And what of the dinosaurs that appeared so unexpectedly? The tylosaurus seemed starving, so could it have come out of a time portal and was lost in the modern world? 

I postulated in a fic once, that perhaps all the lost lands of ERB's Africa were connected, perhaps by an alien intelligance, something like Farmer's crystal tree of time.

But again, if that's true of ERB's Africa, what about that even huger continent, Asia? Burroughs only had one story set there, the Jungle Girl, better known as the Land of Hidden Men. 

It's almost without a doubt that, had ERB set more stories in Asia, many more hidden realms would be uncovered. The there is the lost Viking colony Tarzan finds in North America in the non-canonical Tarzan on the Pricepice. So, no this cannot be a phenomena confined to Africa alone. And then there is the lost Mayan colony in Tarzan and the Castaways, the feudal Japanese culture in The Mucker. There is also all those wired lost realms Korak stumbled upon in his DC comic, while he wondered the earth searching for Merium. That deserves another post, though, as the authors even suggest that Greek goods were real and somehow in control of Korak's fate, and even the inclusion of Circe!