The smallest dinosaur known is the Parvicursor remotus, which was ony 12 to 15 inches long and is estimated to have weighed 4.8 and 5.7 ounces. Parvicursor was a tiny, bipedal feathered theropod dinosaur. It was an Alvarezsaurid, so it only had a single finger, with a claw. It may have used that claw to dig into termite mounds. To escape predators, they would have run quite fast.