Description and Classification

Walkersaurus was a medium-sized herbivorous dinosaur. Adults are estimated to have reached lengths of about 6 to 7 meters (20 to 23 feet) and stood approximately 2.5 meters (8 feet) tall at the hips when standing bipedally. Its weight is estimated to have been around 1 to 1.5 metric tons (2,200 to 3,300 pounds). Like other ornithopods, Walkersaurus was primarily bipedal, meaning it walked and ran on its two strong hind legs. However, it likely possessed the ability to use its shorter forelimbs for support when resting or browsing for low-lying vegetation.

The skull of Walkersaurus was moderately elongated and featured a horny beak, or rhamphotheca, at the front of its jaws, which it would have used to crop plants. Further back in its mouth, it had rows of complex cheek teeth designed for grinding and chewing tough plant material. Walkersaurus is classified as a member of the Ornithopoda, a diverse group of herbivorous dinosaurs that also includes well-known genera such as Iguanodon and Hadrosaurus. More specifically, it is considered part of the Iguanodontia, a clade that shows an evolutionary progression towards the later “duck-billed” dinosaurs. Its skeletal anatomy suggests it was more advanced than early ornithopods like Camptosaurus but not as specialized as the hadrosaurids.

Distinguishing Features

Walkersaurus can be identified by several unique characteristics that set it apart from other related ornithopods:

• Its metatarsals (the long bones in the foot leading to the toes) were unusually elongated relative to its overall leg length, suggesting it may have been a swifter or more agile runner compared to other iguanodontians of similar size.
• A distinctive pattern of ossified tendons along its vertebral column, particularly over the hips and tail base. These bony rods provided increased stiffness and support for the back, possibly aiding in balance during rapid movement or providing leverage for its powerful tail.
• The wear facets on its cheek teeth show a specific pattern, indicating a diet that may have included particularly fibrous or abrasive plant material, different from some of its contemporaries.
• Fossilized trackways attributed to Walkersaurus show a surprisingly narrow gait for an animal of its size, along with evidence of occasional quadrupedal posture, particularly evident in slower-moving track sequences.

Paleoenvironment and Diet

Walkersaurus inhabited a warm, floodplain environment during the Early Cretaceous. This landscape was characterized by meandering rivers, lush conifer forests, fern prairies, and groves of cycads and early flowering plants. The climate was likely seasonal, with distinct wet and dry periods, influencing the availability of vegetation.

As a herbivore, Walkersaurus fed on the diverse plant life available in its habitat. Its beak was suited for nipping off tough stems and leaves, while its powerful jaw muscles and specialized teeth allowed it to effectively process this vegetation. Its diet likely consisted of ferns, cycads, horsetails, and possibly some of the first flowering plants. It shared its ecosystem with a variety of other dinosaurs, including large sauropods such as Astrodon, armored ankylosaurs like Sauropelta, and predatory theropods like the fearsome Acrocanthosaurus, which may have been a potential predator of Walkersaurus.

Significance and Ongoing Research

The discovery of Walkersaurus has contributed significantly to our understanding of ornithopod diversity and evolution in North America during a critical period of the Early Cretaceous. The association of skeletal remains with well-preserved trackways is particularly valuable, as it allows paleontologists to directly link anatomical features with locomotor behavior.

Ongoing research on Walkersaurus focuses on several areas. Detailed biomechanical studies are being conducted to better understand its running capabilities and the function of its narrow gait, using computer models based on its skeletal structure and trackway data. Microwear analysis of its dental surfaces continues, aiming to refine our knowledge of its specific dietary preferences and how it partitioned resources with other herbivores. Furthermore, paleontologists are working to more precisely determine its phylogenetic relationships to other iguanodontians through comparative anatomy and cladistic analysis, helping to clarify the evolutionary pathways within this important group of dinosaurs. Future fossil discoveries may reveal more about its growth stages and social behavior.