Quick Question - Were The Dinosaurs Dead In The Land Before Time?

This video looks at a popular theory on the internet, that all of the dinosaurs in The Land Before Time were killed at the beginning of the film.
P.S. This question is based only on the first Land Before Time movie; I don't even acknowledge the sequels.
Copyright Disclaimer - This video contains copyrighted images and sound. It is an educational study and falls under the "fair use" provisions of copyright law and the first amendment to critique and discuss.