This depiction of the railalomena was illustrated by Philippe Coudray for his 2009 book Guide des Animaux Cachés. In Malagasy, its name is translated to "ancestor of the hippopotamus".

It had been reported since the early 1800s and typically described as a reptile-like creature with a horn in the center of its forehead. The railalomena is said to live among the marshland in Madagascar. Coudray states in his book that it is possible the creature had disappeared when the marshes began to dry up. It is possible, as habitat destruction leads to extinction in many species. He also believes that the creature could possibly still be living in the Madagascar rivers.