He is a Microraptor gui, and first appeared in The Land Before Time XII: The Great Day of the Flyers
Guido is convinced that he's the only one of his kind, having never seen another of his kind before. His origins are unknown, as he apparently has no idea what he is or where he came from. Though he tries to fly, he can only glide for a brief period of time.
He reappears in the TV episode "The Hermit of Black Rock", in which he and Petrie meet an old blind purple Harpactognathus named Swooper, and learns to fly properly. He often appears neurotic or panicky at times, and easily confused.
Guido is a small, bipedal creature around the size of Petrie. He is covered in feathers, with most of his body being teal, his belly color being a lighter shade of teal and the pennaceous feathers on his head, wings and tail being light green.
Though he is a Microraptor per promotional materials, he does not bear a particularly strong resemblance to the genus; he has a toothless, parrot-like beak, no claws and no wings on his legs.