Fossil skull shows a small Cretaceous dinosaur chewed fruit like a parrot

Palaeontologists have described a new dinosaur, Infernogallus jamesi, whose skull was adapted for processing fruit. The animal, a small toothless oviraptorosaur, had a jaw muscle arrangement otherwise seen among living birds only in fruit-eating parrots. The authors, from Stony Brook University, the Royal Ontario Museum (ROM) and the North Dakota Geological Survey, report the work in Nature Communications.

A rare, well-preserved skull

The fossils include a nearly complete, articulated skull and a partial skeleton, now displayed at the ROM. They come from the Hell Creek Formation, which spans parts of Montana, North Dakota, South Dakota and Wyoming. There, the animal lived alongside Tyrannosaurus rex and Triceratops. The name means "hell chicken".

Infernogallus belongs to the caenagnathids, a group of feathered, toothless dinosaurs. It was roughly the size of a turkey and weighed about 12 kg as an adult, making it one of the smallest members of its group. Complete remains of such small dinosaurs are scarce, and the study team led by Dr Gregory Funston noted that, for more than a century, the skull shape of these animals was unknown.

Jaw mechanics built for soft food

Using CT scans, the researchers reconstructed the skull and examined the palatal bones, which form the roof of the mouth. These bones arched downwards into the mouth. As a result, certain jaw muscles ran front to back rather than vertically.

That orientation would have allowed the beak to slide back and forth during chewing, somewhat as in humans. Many other dinosaurs, T. rex among them, are thought to have relied on a rigid, vertical bite. Forward-facing muscles of this kind are uncommon in animals. They occur in mammals with complex chewing and in some fruit-eating birds, such as the vulturine parrot (Psittrichas).

From this similarity, the team concluded that the features probably evolved for the same purpose: working soft food in the mouth instead of leaving the task to the gut. Their analysis of the chewing mechanics suggests the skull was suited to mashing stone fruits to separate the flesh from the seed.

Meat-eating ancestors, fruit-eating descendants

Caenagnathids and their relatives arose from the carnivorous side of the dinosaur family tree, so a fruit specialist was unexpected. The authors also point to parallels between the evolutionary radiation of caenagnathids and that of fruit. According to the report, the group developed its specialised chewing abilities as fruits became larger and more common.

This matters because palaeontologists have struggled to show clear links between dinosaur diversity and the rise of flowering plants. During the Cretaceous, flowering plants replaced cone-bearing plants as the dominant vegetation on land, a shift documented in the fossil record, which includes fossilised fruits.

Implications and open questions

The authors suggest that dinosaurs may have influenced flowering plants as seed dispersers, a role filled today by birds, reptiles and small mammals. The source does not report direct evidence, such as preserved seeds or gut contents, so this remains an inference from anatomy and timing.

The finding also bears on the debate over whether dinosaurs were already in decline before the end-Cretaceous extinction. If species such as Infernogallus occupied new ecological roles, the diversity of dinosaur behaviour at the close of the period may be underestimated. Dr David Evans of the ROM, senior author of the paper, said the discovery shows much remains to be learned about the world of T. rex.

Further work could test the diet hypothesis with other lines of evidence and look for similar jaw adaptations in related caenagnathids and oviraptorosaurs. Comparing them against the timing of fruit evolution in the fossil record would show how closely the two histories track each other.

Source: Rare fossil discovery reveals new dinosaur species that specialized in eating fruit (Phys.org, 31 October 2026).

Image: AI-generated illustration.