A newly discovered dinosaur named Infernogallus jamesi used parrot-like jaw movements to crush fruit 66 million years ago, a fossil study has revealed.
The findings, published in the scientific journal Nature Communications, are based on an exceptionally preserved skull unearthed from the Hell Creek geological formation in the United States.
Researchers discovered that the toothless creature possessed an unusual muscular arrangement that allowed its lower jaw to slide backward and forward. That horizontal motion worked alongside typical up-and-down chewing to process soft foods, echoing the feeding mechanics of modern fruit-eating parrots.
The evidence indicates that the dinosaur belonged to the caenagnathids, a family within the theropod lineage that developed specialized herbivorous habits focused largely on fleshy fruits.
Anatomy of the articulated skull
The discovery centers on an almost complete articulated skull, representing the first specimen of its kind ever identified for caenagnathid dinosaurs. Its remarkable condition allowed paleontologists to inspect delicate cranial structures that show how the animal fed.
Scientists reconstructed the anatomy of the cranium and analyzed the attachment points of the muscles responsible for jaw movement. Non-avian theropod dinosaurs typically relied on a simple vertical snapping motion to open and close their jaws.
In Infernogallus jamesi, researchers identified distinct modifications in the jaw musculature. Working in tandem with specialized structures on the palate, these muscles enabled contact between bony surfaces inside the mouth, allowing the beak to slide back and forth to pulverize soft food.
Such horizontal chewing mechanics are rare among theropods. The researchers noted that the physical arrangement closely mirrors the way certain fruit-eating parrots manipulate and crush food today.
Size and features of Infernogallus jamesi
Infernogallus jamesi was a toothless dinosaur with a horny beak and a lightweight skeleton. According to details from the Royal Ontario Museum, the animal measured roughly the size of a modern turkey and weighed about 12 kilograms.
The creature belonged to the theropods, the diverse group of bipedal saurischian dinosaurs best known for ferocious carnivores such as Tyrannosaurus rex. While most theropods remained predators, caenagnathids evolved bird-like beaks and adapted to plant-based diets.
The fossil was recovered from the Hell Creek formation, a famous rock unit that extends across parts of Montana, North Dakota, South Dakota, and Wyoming. The formation is widely celebrated for its rich deposits of late Cretaceous fossils, documenting the animal and plant communities that thrived just before the mass extinction.
The Royal Ontario Museum in Canada, which provided data on the animal, holds extensive paleontological collections that help scientists track the morphological diversity of late Cretaceous dinosaurs across North America.
Evolution alongside flowering plants
The research adds significant weight to scientific debates regarding the relationship between plant-eating dinosaurs and the rise of flowering plants, known as angiosperms. Angiosperms expanded dramatically across the planet during the Late Cretaceous epoch, between approximately 100.5 million and 66 million years ago.
As flowering plants diversified, they produced larger and more varied fleshy fruits. The authors said caenagnathids developed their specialized skull adaptations during this same window, making them leading candidates among dinosaurs for animals that adapted specifically to eat angiosperm fruits.
Scientists cautioned that one major question about this ecological relationship remains unanswered. The study notes that it is still not clear whether Infernogallus jamesi played a meaningful part in dispersing seeds and helping flowering plants spread.
The findings expand existing knowledge about the diet of dinosaurs living in the final stages of the Cretaceous. The researchers emphasized that the discovery proves dinosaur diversity before the extinction event included far more specialized feeding strategies than previously recognized.
