There are many summonable dinosaurs in scribblenauts, with similar characteristics.
Most Dinosaurs are ridable, but some need to be tamed before hand.
The creature summoned with the word "Dinosaur" is friendly and ridable, but is quick to flee; it usually responds to attacks by becoming scared and running.
Writing several different dinosaurs in a level gets one the "Palientologist" Merit.
Friendly Dinosaurs:
Apatosaurus
Anklyosaurus
Stegosaurus
Triceratops
Pterodactyl
Hostile:
Trex(i.e. T-Rex)
Allosaurus
Spinosaur
Dimetrodon
Velociraptor