In 1909, Lt. Paul Gratz described a "degenerate saurian which one might well confuse with the crocodile, were it not that its skin has no scales and its toes are armed with claws," which he said inhabited swamps near Lake Bangweulu, Northern Rhodesia (Zambia). He called it nsanga, and said that he was shown a piece of its skin on the island of Mbawala. The same year, naturalist Carl Hagenbeck recounted in his autobiography how two separate individuals - a German named Hans Schomburgh and an English hunter - told him about a "huge monster, half elephant, half dragon," which lived in the Congo swamps. Joseph Menges, another naturalist, told Hagenbeck that "some kind of dinosaur, seemingly akin to the brontosaurs," lived in the swamps. Hagenbeck sent an expedition to the Congo to search for the monster, but the effort was quickly aborted due to disease and hostile natives.
Hans Schomburgh also recounted to Hagenbeck that hippopotami were absent from Lake Bangweulu; the natives said this was because of the depredations of a monster which inhabited the lake. In the Dilolo swamps, he heard tales of a similar creature which the natives called chimpekwe.
In 1913, Capt. Freiherr von Stein zu Lausnitz was sent by the German government to explore the Cameroon. Von Stein wrote of an animal called in the local tongue mokele-mbembe, said to inhabit the areas near the Ubangi, Sanga, and Ikelemba Rivers. Von Stein described the creature thus:
The animal is said to be of a brownish-gray color with a smooth skin, its size approximately that of an elephant; at least that of a hippopotamus. It is said to have a long and very flexible neck and only one tooth but a very long one; some say it is a horn. A few spoke about a long muscular tail like that of an alligator ... It is said to climb the shore even at daytime in search of food; its diet is said to be entirely vegetable ... At the Ssombo River I was shown a path said to have been made by this animal in order to get at its food. The path was fresh and there were plants of the described type [a liana] nearby...
In the 1920s, several mokele-mbembe-seeking expeditions were organized, sparked by several hoaxed stories reported in several newspapers. In 1927, the book Trader Horn, a memoir of the author's time in Gabon (specifically along the Ogooue River), was written by Englishman Alfred Aloysius Smith. Smith recorded hearing of a creature called the jago-nini. He identified it with the amali, a creature whose tracks he had seen.
After Trader Horn, the Congo "dinosaur" was nearly forgotten until 1948, when cryptozoologist Ivan T. Sanderson wrote an article about them. With the publication of Bernard Heuvelmans' classic cryptozoological work On the Track of Unknown Animals in 1958 interest in the "dinosaur" was sparked once again.
In 1960, herpetologist James H. Powell, Jr., took interest in the African dragons and organized an expedition to the Congo in 1972. Powell's expedition was fraught with problems (the United States and the Congo had poor relations at the time), but he finally launched the expedition in 1976. Powell went to Gabon instead (the region where Trader Horn had collected his reports). Powell was quick to realize they were probably identical to the mokele-mbembe. Furthermore, Powell heard local legends of the n'yamala, and locals identified pictures of a sauropod dinosaur as bearing the most resemblance to the animal.
Powell launched another expedition in 1980, but this time cryptozoologist Roy P. Mackal went along. Powell and Mackal found that a large number of reports came from the banks of the Likouala-aux-herbes River near Lake Tele. They said that most witnesses maintained that the animal was between 15-30 feet long (a long neck accounted for much of the length). The creature is also said to be a rust color, and some have been seen to have a frill or crest. A report was collected of a 1959 incident in which a mokele-mbembe had been killed, and its flesh eaten - all the natives who ate its flesh died.
Yet another expedition was organized in 1981 - this time composed of Mackal, J. Richard Greenwell, M. Justin Wilkinson, and Congolese zoologist Marcellin Agnagna. The expedition encountered what they believed was a Congo "dinosaur" along the Likouala River, when they heard a large animal leaping into the water near Epena. They also found a path of broken branches supposedly made by the animal, as well as a number of footprints.
An expedition mounted by engineer Herman Regusters managed to make its way to Lake Tele, where Regusters and his wife heard the growls and roars of some creature. They also claimed to have seen some large animal moving through the brush. Regusters also said he saw the creature in the lake, and estimated it was 30-35 feet long.
Heuvelmans, Bernard. On the Track of Unknown Animals. London: Kegan Paul, 1995.
Mackal, Roy. Searching for Hidden Animals. Garden City, NY: Doubleday, 1980.