Parksosaurus (Park’s lizard)
Parksosaurus (Park’s lizard)
Named By : C. M. Sternberg - 1937
Diet : Herbivore
Size : Estimated 2.5 – 3 meters long
Type of Dinosaur : Euornithopod
Type Species : P. warreni (type)
Found in : Canada, Alberta - Horseshoe Cnayon Formation
When it Lived : Late Cretaceous, 76-74 million years ago
Parksosaurus, which means “William Parks’s lizard”, is a genus neornithischian dinosaur from the Alberta-Canada’s Upper Cretaceous Horseshoe Canyon Formation. It was based on a large portion of a partially articulated skull and skeleton, which shows it to be a small, herbivorous, bipedal dinosaur. It is one the few known non-hadrosaurid ornithopods that existed in North America at the end of Cretaceous, approximately 70 million years ago.
It is rare to get an exact estimate of the entire animal’s size. Gregory S. Paul in 2010 estimated that the length was 2.5 meters and the weight at forty-five kg. William Parks estimated that the hindlimb of his T.warreni was approximately the same length as the one of Thescelosaurus neglectedus (93.5 cm (3.05 ft.) for T.warreni and 95.5 cm (3.13 ft.) for T.negus). This is despite the fact that the T. neglectus’ shin was longer than the T.warreni’s thigh. The animal would have been similar to Thescelosaurus in terms of linear dimensions, despite some differences (6.56-8.2 meters) at the hips and 22.5 meters (6.56-8.2 feet) at the length. It would have been lighter if the proportional differences were greater, since less weight was near the thigh. It had thin, partially ossified intercostal cartilaginous plates (like Thescelosaurus) along its ribs. Strong shoulder girdles were found. Parksosaurus had at most 18 teeth in its maxilla, and around twenty in the lower jaw. The number of teeth in his premaxilla is not known.
William Parks, a paleontologist, described skeleton number ROM 804 as Thescelosaurus Warreni in 1926. It had been found in the Edmonton Formation on the Red Deer River in 1922. It consisted of a partial skull, missing the beak, most of the left pectoral and sternal girdles (including a suprascapula which is more common in lizards but which was thought to have been present in ornithopods in cartilaginous forms), the left arm, ribs, and sternal elements. The animal’s body had fallen to its left, with most of its right side destroyed prior to burial. Additionally, the neck had been lost and the head was separated from the body. Parks distinguished the new species from T. neglectedus based on leg proportions. T. warreni had longer legs than T. neglectus and longer toes.
Charles M. Sternberg discovered the specimen and named it Thescelosaurus. He then revisited T. warreni to determine if it deserved its own genus. Although the abstract was not typical, the specimen had been well-described. He presented a more detailed comparison in 1940 and discovered a few differences between the genera throughout the body. Parksosaurus was assigned to the Hypsilophodontinae, with Hypsilophodon & Dysalotosaurus. Thescelosaurus was to the Thescelosaurinae. The genus was not much known until Peter Galton’s 1970s revision of Hypsilophodonts. Parksosaurus received a redescription in 1973, wherein it was considered to be related to a Hypsilophodon\Laosaurus\L. minimus lineage. It was then relegated to obscurity.
George Olshevsky changed the species name from P. warrenae to P. warrenae, in 1992. This was because the species’ name is named after a woman (Mrs. H. D. Warren, who funded the research), however, outside of Internet sites, the original spelling is preferred.