Gigantophis fed on pig-sized proboscideans, such as Moeritherium, which were distant cousins of the modern elephants. The giant snake also ate crocodiles and other large reptiles. Gigantophis would largely be an aquatic snake, hiding underwater until it was time to strike. It was a constrictor, like modern day boas and pythons. However it was related to neither of those two snake families, instead it was part of the now extinct genus Madtsoiidae.