He is the adoptive son of Heart and thought that his name was Umasou after Heart said he looked delicious. He is a small pink ankylosaurus with a orange shell and red spikes and tail club. Umasou is referred to in the movie as a 'Hard-Back' dinoasaur. 

A Tyrannosaurus called Heart was raised by a herbivorous dinosaur. As he grew up, he was scared by other dinosaurs. One day, Heart meets a baby Ankylosaurus and he names the baby "Umasou (looks delicious)". Umasou started to be attached to Heart and a strange family love develops between the two.