Screech and Thud are the two Utahraptor companions of Red Claw and the secondary antagonists in The Land Before Time TV series.
There seems to be a symbiotic relationship between Red Claw, Screech & Thud as Ruby has once said "Where ever Screech and Thud are, Red Claw is never far behind" and in at least one episode, The Hidden Canyon, the Fast Biters actually led Red Claw to a breach in the wall protecting the Great Valley from sharpteeth. In later episodes, Screech and Thud have been seen hunting without Red Claw.
How or why they hunt together is unknown, though it could do with simple symbiosis: Screech & Thud use their smarts, small size and greater agility to access places Red Claw can't get to when hunting and flush out prey while Red Claw's brute strength and ferocity protects them from being attacked or eaten themselves and guarantees them an easy meal.
Nonetheless, it is almost impossible for Littlefoot and his friends to encounter one without encountering all three and at fulls strength. They make an incredible, not to mention lethal, team of carnivores.
Screech is a blue raptor with dark blue stripes and pale underbelly. Thud is the green raptor with dark green stripes and pale underbelly.