Gallimimus

Gallimimus was a speedy predator, the largest of its type. They were called chicken mimics because they probably moved like modern flightless birds. Unlike other meat-eaters, Gallimimus had no teeth. In fact, it had a very small head. This was probably one of the fastest dinosaurs, with speed like a modern cheetah, it could probably run up to 60 mph.

With its small, toothless head, it is believed that Gallimimus probably had a diet of insects, small animals, eggs and maybe even some plants. They hand very long fingers and long arms, which they could use for digging or grabbing eggs. They had a much longer neck that any other therapod dinosaur. In Jurassic Turok they were shown as large flock, but we don't know if that was real or movie behavior.

More real-life information: Gallimimus at Wikipedia.

Appearance
A Gallimimus holds a height of 2 meters (6.6 feet) at the hip, length of 8 meters (26 feet), and weight of 160-440kg (970 pounds).