Ichthyovenator dinosaur, illustration. This was a large fish-eating theropod that lived during the Early Cretaceous (around 125 to 113 million years ago). Ichthyovenator dinosaurs could weigh around 2,000 kilograms and grew up to around 8.5 metres in length. In 2010, the first Ichthyovenator fossil was found in Laos. A main characteristic of this dinosaur was that it had a wavy sail down its back that separated to form two sails.