The dinosaurs lived about 70 million years ago and sported huge, round guts; stumpy legs; a long neck and a turtle-like head and beak. (Agencies)
"Not only is this the largest colony of non-avian theropods, but this is the best documented site," said study co-author Yoshitsugu Kobayashi, a vertebrate paleontologist at Hokkaido University in Japan.
The discovery suggests the odd little creatures were social animals. Therizinosaurs were herbivores, despite being members of the carnivorous group theropods, which includes the deadly king of the predators Tyrannosaurus rex.
They also had huge three-digit claws that may have been used to grasp branches and scrape up plant material.
Researchers discovered the nest while in southeastern Mongolia in 2011. They excavated a total of 17 clutches, for a total of about 75 eggs the following year.
The eggs were round, with about a 3 centimeters diameter and rough outer shells. The dinosaurs would have been about 99 kilograms when full-grown, the report said.
The presence of eggshells inside the eggs suggested that most of the baby dinosaurs had hatched. The discovery supports the theory that therizinosaurs were social animals that hung out together.
The dinosaurs lived about 70 million years ago and sported huge, round guts; stumpy legs; a long neck and a turtle-like head and beak.