The SS Ahnenerbe expedition to Tibet discovered a sacred cave that Buddhist Monks believed led to an underworld where the sacred city of Shambhala was located. The monks were persuaded to reveal the location of the cavern by Her Flick, a Gestapo agent spying on Himmler's Expedition for Goering.
The cave certainly opened into somewhere, a mysterious world inhabited by prehistoric monsters as detailed by Jules Verne in his supposed novel 'Journey to the Centre of the Earth'.
Local humans had domesticated a bipedal carnivore. The Stormtruppen seized various examples for study and a breeding program. Unfortunately, all the animals acquired were males, as indicated by the mating display on the head. Nevertheless they trained some to be SS-Kavallerie abd named their unit after the expedition leader, Dr Ernst Schäfer.
One soldier in each troop was armed with an MG 34. The mounts were surprisingly indifferent to gunfire.
Alas, the expedition got lost in the complex of tunnels trying to reach the 'surface' and emerged in Afghanistan, only to find the world was not quite as they remember it.
Models by Eureka.