Madtsoia is an extinct genus of madtsoiid snakes. It is known from the Eocene of Argentina (M. bai),[1] the Paleocene of Brazil (M. camposi),[2] the Late Cretaceous (Maastrichtian) of India (M. pisdurensis),[1] and the Late Cretaceous (Maastrichtian) of Madagascar (M. madagascariensis).[3] The type species (M. bai) was the largest with an estimated length of 9–10 m (30–33 ft),[4][5] and the other three species were smaller.[3][2][1] A 5.1 m (17 ft) long M. madagascariensis would have weighed 50 kg (110 lb), but an isolated specimen suggests that this species reached 8 m (26 ft) in maximum length.[3]