Pteranoid

Pteranoid (プテラノイド) is a sub-boss from Mega Man X5 that appears in Mattrex's stage if the player takes the upper path instead of using the Ride Armor below the lava. It's a Pteranodon robot that releases fireballs from the mouth and follows the player through a area with lava.

Trivia
It acts similar to the Mecha Dragon from Mega Man 2.