The creature is described as rather large, with size estimate ranging from as small as a hippo to the size of an elephant. The largest reptiles, the saltwater Crocodile has the required length, but its height, even at the maximum is lower than waist height.
The Komodo Mbèmbé
My next guess was at the Komodo dragon, the largest lizard. I had thought maybe this could be a freakishly large specimen. Fortunatly the largest ever found was 3.13 meters long (around 9 feet) making for a good base point. But unfortunelty the skeletal structure of lizards make even the komodo dragons size difficult to support, I doubt that even an artificially created Komodo Mbèmbé could support the weight, never mind a naturally evolved one. The next problem is more subtle, Island Gigantism, the thing that made the Moa, Haast's Eagle and Tenerife giant rat so, well, giant. The Komodo dragon is only found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang, and Padar, most of these it is the dominant predator. around 4 million years ago a similar species was found in Austrailia though even going back, we have yet another problem. Its diet, meat; big animals need a lot of food to be big, shocker I know, with other large predators in the congo, even if our Komodo Mbèmbé wasn't outcompeted, it would have extreme difficulty hunting in the jungle.
It was around here I realized I was in over my head. Carnivorous giants are super rare (with the largest land predator being the polar bear, which is much too small) so carnivores were out of the picture. The bone structure of lizard limbs didn't really even allow for the size or shape we need;
I then went down into the line of mammals, specifically native african giants. This is when I discovered the perfect candidate; the giant Pangolin.
At an average of three feet, may seem too small, but keep in mind that mammals scale up in size rather well, escpecially when compared to lizards. ALso as an insectivore that feed on massive colonies we have a base for a large stable diet, though for the desired size (minimum of a hippo) we need to edit its diet to include leaves and fruit, this altered diet may have even caused the gigantism. The Mokèlé-mbèmbé is almost always described with a long neck, which is why I almost quit this Mokèlé-Pangolin endeavor until I realized that by including fruit as a staple within its diet, I have an double excuse for a long neck; it allows for the creatures to easily grab at higher up fruit and leaves, much like the giraffe.
In case this didn't tickle your ''Of course'' Fancy, its habitat also lines up with sightings of the Mokèlé-mbèmbé;