Researchers from Yale University have pieced together fossil evidence from a new specimen that they think could be a crucial ancestor of birds and the first known example of an evolved beak. The fossilized animal, known as Ichthyornis dispar, was alive 100 million years ago in North America.
Partial fragments of this dinosaurian species have been known about for 150 years, with the fossils even known about by Darwin. Now, researchers have combined a complete skull and two previously overlooked cranial elements from the original Yale specimen to reconstruct what this animal must have looked like and its importance in connecting dinosaurs to modern birds. The results are published in Nature.
"Right under our noses this whole time was an amazing, transitional bird," principal investigator, professor Bhart-Anjan Bhullar, said in a statement. "It has a modern-looking brain along with a remarkably dinosaurian jaw muscle configuration."
"The first beak was a horn-covered pincer tip at the end of the jaw," Bhullar added. "The remainder of the jaw was filled with teeth. At its origin, the beak was a precision grasping mechanism that served as a surrogate hand as the hands transformed into wings."
To arrive at the new findings, the team used CT scans and combined the Yale specimen from those at other institutions like the Sternberg Museum of Natural History and the Alabama Museum of Natural History.
"The fossil record provides our only direct evidence of the evolutionary transformations that have given rise to modern forms," co-author Daniel Field, from the University of Bath, added. "This extraordinary new specimen reveals the surprisingly late retention of dinosaur-like features in the skull of Ichthyornis – one of the closest-known relatives of modern birds from the Age of Reptiles."
The findings provide an insight into how the skulls and beaks of modern birds eventually formed. It also gives us new insight into how the brain of this ancient creature was structured. It appears that the brain was quite bird-like, but with characteristics in the temporal region of the skull that places them firmly in the dinosaur class. This suggests that it’s highly likely that birds evolved their brain first.
"Each new discovery has reinforced our previous conclusions. The skull of Ichthyornis even substantiates our molecular finding that the beak and palate are patterned by the same genes," Bhullar said. "The story of the evolution of birds, the most species-rich group of vertebrates on land, is one of the most important in all of history. It is, after all, still the age of dinosaurs."