BBC Online: Walking with Dinosaurs
Provides a time line from the late Triassic to the early Cretaceous.
http://www.bbc.co.uk/dinosaurs

The Dinosauria
Extensive information about the dinosaurs from the University of California Museum of Paleontology
http://www.ucmp.berkeley.edu/diapsids/dinosaur.html

Zoom Dinosaurs
Dinosaurs, dinosaur anatomy and dinosaur extinction at Zoom Dinosaurs. Learn about many different dinosaur genera, dinosaur anatomy, dinosaur extinction, ...
http://www.enchantedlearning.com/subjects/dinosaurs/