Silent Knight Shō (サイレントナイト翔?) is a manga created by Masami Kurumada. The story is that every human descends from an animal, and in the story various characters can call upon armors from these animals.
Sho is seen fighting with a local gang that terrorizes the nearby town, he defeats them rather quickly with his powers. And is joined by his pet Pii-tan a falcon, whom he have been friends with since childhood. Later as the gang resumes their activities and are driving recklessly through town, they are forcefully stopped by a T. rex. Though its appearance differs from a usual T. rex in that it looks like it has an armor. Even though it kills the gang, they are not his mission. Instead he is looking for a traitor who happens to be Shirin, who wields a Fairy armor. Sho finds him eventually face to face with Shirin who is as small as a fairy with her armor on, badly hurt. The T. rex goes by the name Tyranno and find Sho with Shirin and wastes no time and tries to stomp them to death. Pii-tan comes to the rescue and manages to draw Tyranno's attention away from Sho, who flees into a nearby house with Shirin.
But pii-tan is struck badly by Tyranno and falls to its death, can the T. rex heads for the house. As Shirin tries to explain what's happening to Sho, Tyranno stomps right through the roof. But as Sho has felt the near death of pii-tan he awakens his armor and stops Tyranno. He eventually defeats Tyranno, and it's revealed that he's a human as well. But since he has equipped his armor he enlarges to the size of a T. rex.