Paleontologists have discovered that some birds once used teeth to chomp down on their prey.
Researchers working in the U.S. and China examined a new fossil specimen of Sulcavis geeorum, an early ancestor of today’s birds that lived between 121 million to 125 million years ago in the Early Cretaceous period.
The bird’s teeth were likely evolved for a special ‘durophagous’ diet, allowing it to chew up harder-shelled meals like crabs and large beetles.
According to the study published in the Journal of Vertebrate Paleontology, the specimen, discovered in China, suggests greater ecological diversity among an early group of early birds called enantiornithines.
This is the first bird species to have been discovered with such grooves, ridges, striations, serrated edges or any other form of dental ornamentation, said researchers.
“While other birds were losing their teeth, enantiornithines were evolving new morphologies and dental specializations,” explained Jingmai O’Connor of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, lead author of the study.
“We still don’t understand why enantiornithines were so successful in the Cretaceous but then died out – maybe differences in diet played a part.”
In an exclusive interview with the Science Recorder, O’Connor described how her team happened upon the exciting finding.
After being asked to study new bird specimens at the Beijing Museum of Natural History, O’Connor noticed the “unusual striations” of the Sulcavis geeorum on display and “decided to describe the specimen, recognizing that it was a new species.”
While there is no way to determine exactly what the toothy bird ate, the researchers used “homologous morphologies” of known animals to determine its diet. “Other animals with similar tooth ornamentations eat hard foods,” said O’Connor, “so maybe so did Sulcavis. But there is nothing to support this directly.”
So if the birds were able to feast on a wider range of hard foods, why did they go exctinct?
“Diet may in fact have been a dividing difference,” said O’Connor. “There is no evidence that enantiornithines had a well developed gastric mill like ornithuromorphs, the group that includes living birds. This may have lead to their extinction because enantiornithines evolved almost all the same flight specializations by the Late Cretaceous, such as a large fully keeled sternum.”
The group’s findings also hold significant implications for the evolution of modern birds.
“What’s interesting is this is one study in which enantiornithines—Sulcavis and its kin—do not so much parallel ornithuromorphs,” explained O’Connor. “While both groups evolved advanced flight specialization in parallel, they seemed to have diverged when it comes to diet. Ornithuromorphs and most other groups of birds tended to reduce their dentition while the enantiornithines explored new morphospace.”
O’Connor plans to expand on the discovery to further unravel the mysteries surrounding animal evolution and extinction in the Early Cretaceous period.
“This has lead me to think of other approaches to understanding ancient diet,” O’Connor said. “I plan to use methods employed by mammologists on the tooth enamel to see if we can find additional clues.”