|Information in this article is non-canon|
This is the term for Dinilysia. A Slithering Sharptooth appears in the movie Land Before Time XXIII: The Time of Choosing in a flashback to LIttlefoot's younger days, when he was with his mother. His mother saved him from a Slihering Sharptooth when he was about a year old.
Later, in the movie The Land Before Time XXIV: The Incredible Journey, Littlefoot, now about 25, saves youngsters Atto and Nigel from one, in much the same manner as his mother had saved him.