Compsognathus, komp SOG nuh thuhs, was one of the smallest known dinosaurs. It grew to about the size of a chicken or turkey, measuring around 2 1/2 feet (0.8 meter) long and weighing approximately 6 to 7 pounds (2.7 to 3.2 kilograms). The animal lived from 155 million to 145 million years ago, during the Late Jurassic Period.