Mo, Littlefoot's "mud brother".

Mo is a colourful opthalmosaurus, which is referred to as a swimmer (which also describes any animal in The Land Before Time series which swims) in The Land Before Time films and TV series. He is referred to by Littlefoot as his "mud brother". He will meet Winnie the Pooh, Ash Ketchum, and their friends in Pooh's Adventures of The Land Before Time IX: Journey to Big Water.