Parksosaurus was an ornithopod dinosaur related to Othnelia, named after William Parks, the palaeontologist, who discovered it first in 1937. It was a smallish dinosaur - roughly 2.5 m long. It didn't have any particular anatomical features and was a distant relative of the bigger hadrosaurs, such as Anatotitan, also featured in WWD. It was also a close relative of Thescelosaurus.
Explicit estimates of the entire size of the animal are rare; in 2010 Gregory S. Paul estimated the length at 2.5 meters, the weight at 45 kilograms.
William Parks found the hindlimb of his T. warreni to be about the same length overall as that of Thescelosaurus neglectus (93.0 centimeters (3.05 ft) for T. warreni versus 95.5 centimeters (3.13 ft) for T. neglectus), even though the shin was shorter than the thigh in T. neglectus, the opposite of T. warreni.
Thus, the animal would have been comparable to the better-known Thescelosaurus in linear dimensions, despite proportional differences (around 1 meter (3.3 ft) tall at the hips, 2-2.5 meters (6.56-8.2 ft) long).
The proportional differences probably would have made it lighter, though, as less weight was concentrated near the thigh. Like Thescelosaurus, it had thin partly ossified cartilaginous (intercostal) plates along the ribs.
The shoulder girdle was robust.
Parksosaurus had at least eighteen teeth in the maxilla and about twenty in the lower jaw; the number of teeth in the premaxilla is unknown.
It, like other Thelescosaurs were probably burrowers.