Description and Classification

Haya was a relatively small dinosaur, measuring about 1.5 to 2 meters (5 to 6.5 feet) in length and likely weighing around 15 kilograms (33 pounds). It walked on two legs (bipedal) and had a slender build, suggesting it was a fairly agile creature. Haya possessed a beaked mouth, typical of herbivorous ornithischian dinosaurs, which it would have used to crop vegetation, along with teeth further back in the jaw for chewing.

Haya is classified as an ornithischian dinosaur, belonging to the group Ornithopoda. Ornithopods are a diverse group of plant-eating dinosaurs that also includes well-known dinosaurs like Iguanodon and the duck-billed hadrosaurs. Haya is considered a basal, or early, member of this group, meaning it represents an earlier stage in ornithopod evolution. Its discovery helps paleontologists understand the early diversification of these plant-eaters in Asia, showing how they spread and changed over millions of years.

Distinguishing Features

• Small, lightweight body, typically around 1.5 to 2 meters (5 to 6.5 feet) long.
• Walked on two powerful hind legs, allowing for agile movement to escape predators or find food.
• Possessed a toothless beak at the front of its jaws for nipping off plants, with rows of chewing teeth further back in the mouth.
• Multiple specimens were found with clusters of gastroliths (gizzard stones) in their abdominal region. These stones were swallowed to help grind tough plant food in a specialized part of the stomach.
• Certain features of its skeleton, such as strong shoulders and relatively short, robust forelimbs, have led some scientists to suggest Haya might have been capable of digging burrows. This is similar to another small ornithopod dinosaur, Oryctodromeus.

Paleoenvironment and Diet

Haya lived in what is now the Gobi Desert in Mongolia. During the Late Cretaceous period, this region was not as dry as it is today. It was likely a semi-arid environment with distinct wet and dry seasons. The landscape probably consisted of floodplains, river channels, and open woodlands, supporting a variety of plant life that Haya could eat.

As a herbivore, Haya‘s diet would have consisted of low-growing plants such as ferns, cycads, and possibly early flowering plants. Its beak was well-suited for snipping off leaves and stems. The numerous gastroliths found with Haya fossils played an important role in its digestion. These stones acted much like grit in a bird’s gizzard, grinding up tough plant material before it passed further into the digestive system, allowing Haya to get more nutrients from its food.

Significance and Ongoing Research

The discovery of Haya has provided valuable insights into the diversity and evolution of small ornithopod dinosaurs in Asia during the Late Cretaceous. Its well-preserved remains, including multiple individuals found together, offer a good look at its anatomy, growth, and potential behaviors.

Ongoing research on Haya continues to explore its exact position within the ornithopod family tree and its relationship to other small herbivorous dinosaurs from around the world. The clear evidence for gastroliths in Haya is particularly important, reinforcing our understanding of how these dinosaurs processed their food. Furthermore, the hypothesis that Haya may have dug burrows is an exciting area of study. If confirmed, it would add another example of burrowing behavior in non-avian dinosaurs, showing they had a wider range of lifestyles than once thought. Future studies will likely involve more detailed comparisons with other dinosaurs and further analysis of the rock formations where Haya fossils are found.