Troodon was a small bird-like dinosaur with long, slender hindlimbs. It had grasping hands and two large retractable claws on the second toe of each foot.
Troodon lived among the streams and deltas of coastal plains on the island continent of Larimidia alongside Euoplocephalus, Dromaeosaurus and Nanuqsaurus.
The braincase of Troodon shows a well developed sense of hearing.
Troodon teeth are serrated – a feature often seen in animals eating a significant amount of plant food. Troodon is therefore thought to have been omnivorous.
We know that Troodon had a better sense of smell than modern-day birds, but a worse sense of smell than crocodiles and larger theropod dinosaurs like Tyrannosaurus rex.
In 1983, Jack Horner uncovered dinosaur eggs and nests within the Two Medicine Formation (a strip of rock dated to the Late Cretaceous period) in Montana. Horner, along with fellow palaeontologist David Varrichio, described a partial skeleton of an adult Troodon brooding a clutch of at least five eggs, just like a bird.
Height: 1m (3.28ft)
Length: 2.4m (7.87ft)
Weight: 49.9kg (110lbs)
Top speed: 39kph (24.23mph)
Vision: Troodon had huge eyes which would have enabled it to hunt at night or during the long, dark polar winters.
Skin: Troodon comes from a lineage of dinosaurs that had feathers. Most scientists hypothesise that Troodon would have had them too.
Brain: Troodon is thought to be the most intelligent dinosaur discovered so far. Its EQ or encephalisation quotient (a measure of brain size compared to body size) was six times higher than the dinosaur average.
Prey: There is a possibility that Troodon hunted in packs. If this were the case, they could have taken down much larger prey than would have been possible individually. However, we have no real evidence of pack behaviour as yet.
Bite: The teeth of Troodon are serrated, which is often a characteristic of herbivores. But because Troodon runs fast, has excellent stereoscopic vision, grasping hands and sharp claws, it is thought to have been carnivorous. Some palaeontologists believe it might have been omnivorous.
Nest: Troodon nests were built from sediment and were about 1m (3ft) in diameter with a pronounced rim. There would have been about 20 eggs in each nest.