Researchers have discovered a new dog-sized dinosaur, Fona herzogae, in Utah, believed to have lived underground 99 million years ago, showing anatomical features hinting at burrowing behavior. The fossils were found in good condition, suggesting the dinosaur might have been underground before death, aiding preservation. Another new species, Harenadraco prima, the first troodontid dinosaur from the Late Cretaceous Baruungoyot Formation of Mongolia, exhibits adaptations for high speed and agility in its environment. Paleontologists are surprised by the burrowing behavior of dinosaurs like Fona, showcasing adaptations for digging and underground life, challenging previous assumptions about dinosaur behavior and diversity.