Stony Brook Paleontologist Dinosaur Discovery Reveals a Specialized Fruit Eater
A dinosaur discovery by an international team of paleontologists from Stony Brook University, Royal Ontario Museum (ROM) and the North Dakota Geological Survey revealed a new species that makes it the first known dinosaur that specifically ate fruit.
Infernogallus jamesi, a type of small bird-like, bipedal dinosaur (oviraptorosaur) had chewing muscles for mashing soft food. It lived during the Cretaceous period, some 145 to 66 million years ago.
Led by Greg Funston, assistant professor in the Department of Anatomical Sciences in the Renaissance School of Medicine (RSOM) at Stony Brook University, the research analyzed the chewing muscles of the new species. The team’s findings showed that it had a unique arrangement only seen in fruit-eating parrots today.
Details of the discovery are explained in a paper published in Nature Communications.
“We knew dinosaurs evolved to fill so many different roles in ecosystems in the Cretaceous, but we never expected to discover fruit-eating dinosaurs,” said Funston, the corresponding author. “For more than 100 years, we didn’t know what the skulls of these animals looked like. Now, we know they were even weirder than we could have predicted.”
Infernogallus, meaning “hell chicken,” was so named because the fossils — including a nearly complete, articulated skull and partial skeleton, currently on display at the Royal Ontario Museum — were found in the Hell Creek Formation in the U.S. (stretching across Montana, North Dakota, South Dakota and Wyoming), where it would have lived alongside T. rex and Triceratops.
Belonging to a group of toothless, feathered dinosaurs called caenagnathids, Infernogallus
But perhaps this “hell chicken” had hell-bent behavior to survive, as it lived among the ravenous carnivores and lumbering herbivores that roamed the Cretaceous landscape. Yet Infernogallus roamed about and only ate the plants that began to flower and produce fruit.
The unique evolution of the fruit eater
Curiously, Infernogallus and its relatives evolved from the meat-eating side of the dinosaur tree. Detailed analysis of its chewing mechanics shows that its skull was specialized for mashing stone fruits to remove the flesh from the main seed. This came as a surprise, because paleontologists had previously struggled to show any clear links between dinosaur diversity and the evolution of flowering plants. However, this discovery underscores parallels between the evolutionary radiations of caenagnathids and fruit, with caenagnathids evolving their specialized chewing capabilities as fruits became bigger and more common.
“It’s pretty rare for animals to become specialized for a diet of fruit, so when it happens, it comes with some remarkable adaptations,” said Thomas Dudgeon, current Rebanks Postdoctoral Research Fellow at ROM and one of the co-authors of the research paper. “The anatomy of Infernogallus is bizarre among dinosaurs, and we quickly realized that we were dealing with something special.”
Infernogallus’ ability to chew fruit can be seen in the adaptations to its palatal bones — the parts of the skull that make up the roof of the mouth. Using CT scans to reconstruct the skull, the researchers found that these bones arched downwards into the mouth itself, which made certain muscles face front-to-back instead of up and down. This would have enabled a chewing motion where the beak slid back and forth, like in a human, instead of the rigid vertical bite of T. rex and other dinosaurs.
These forward-facing muscles are rare in the animal kingdom — though they are present in mammals like humans who demonstrate complex chewing, and in some birds that specialize in fruit-eating, like the Vulturine Parrot (Psittrichas). The uniqueness of this muscle organization led the researchers to conclude that these adaptations likely evolved for the same reason: processing soft foods — such as fruit — in the mouth instead of the gut.
The revelation that Infernogallus was a fruit-eating dinosaur is additionally significant, the authors say, as the discovery suggests that dinosaurs may have had an unrecognized impact on the evolution of flowering plants as seed-dispersers — an important role filled by birds, reptiles and small mammals today.
During the Cretaceous, flowering plants took over from cone-bearing plants as the major vegetation on land — as seen in the fossil record, which includes fossilized fruits.
“Complete remains of small dinosaurs like Infernogallus are very rare in the fossil record. The strange skull of Infernogallus is an exciting find because it reveals surprising insights into dinosaur evolution and feeding specialization,” added David Evans, chief curator, Natural History & Temerty Chair in Vertebrate Palaeontology at ROM and senior author of the paper. “This discovery shows that we still have a lot to learn about the world of T. rex, and about dinosaurs more generally.”