The Kasai Rex: The Kassaisaurus April Fools' Hoax of the Belgian Congo

1 April 1932. The German weekly Kölnische Illustrierte Zeitung ran a double page spread titled "Der 'Kassaisaurus,' das letzte Urweltgeschöpf". Five photographs. A portrait of a Swedish plantation overseer named J. C. Johanson. A map detail. A clipping about the Schomburgk expedition. And two pictures of a monster.

The date matters. It was an April Fools' feature.

According to the story, the encounter took place on 16 February 1932 in the Kasai valley of the Belgian Congo. Johanson was travelling with a local servant, called only "the boy", who carried his rifle. About 50 yards from a group of animals, Johanson saw "a monster, about 16 yards in length, with a lizard's head and tail." Then it was gone. "Suddenly the monster vanished, with a remarkably rapid movement."

The servant was gone too. "The boy had taken French leave, carrying the rifle with him." Unarmed, Johanson came upon the creature again at a swamp. It was "tearing lumps from a dead rhino. It was covered in ooze." He said: "I could hear the crunching of rhino bones in the lizard's mouth."

He remembered his camera. "Just as I clicked, it jumped into deep water." Afterwards, he said, "For eight days I lay in a fever, unconscious nearly all the time."

A few days after 1 April, the magazine published a follow up admitting the fabrication. Its explanation was plain: "Photographs of monitor lizards… were mounted in appropriate proportions in African jungle images."

The confession did not travel. In July 1932 South African papers reprinted the story as fact. The Cape Argus ran "Mystery animal of African swamps?" on 5 July and "Met the mystery monster: Terrifying encounter in African swamp" two days later. Another headline declared "'Chepekwe does exist'". The Rhodesia Herald followed from mid July with items such as "A 4-ton lizard". Coverage ran until March 1933.

No colonial or scientific body ever looked into it. In 1955 Bernard Heuvelmans called the rhino picture a "manufactured photomontage". In 2026 Markus Hemmler traced the story to its German origin and found the backgrounds. Both came from Carl Georg Schillings' book Mit Blitzlicht und Büchse (1905): a rhinoceros at a water hole and East African elephants. Monitor lizards had been pasted on top. Inconsistent scale and lighting, light halos and blackened retouching give them away. Hemmler also notes that Heuvelmans later wrongly linked the material to the separate chipekwe reports of Hans Schomburgk and Grobler.

Johanson's text never mentions a dinosaur. The "saurus" came from the editors. In 1955 Le Journal de Tintin asked in a caption whether the Chipekwe might be a tyrannosaur, and Gino D'Achille's illustration gave the beast a theropod look. The name "Kasai rex" appeared somewhere between the late 1990s and 2003. With it came a new version. A "John Johnson" who fainted, then woke to see a reddish animal "with blackish-coloured stripes", about 13 m long, with "a long snout and numerous teeth". Karl Shuker found no original source for those claims.

Roy P. Mackal reproduced the Herald text in his 1987 book on Mokele-mbembe, and the tale passed through cryptozoology dictionaries and blogs for decades. Today it stands as a confirmed hoax. A revealing one. It shows how an April joke, reprinted without its retraction, can grow into a living dinosaur.