Experts say that fragments of a skeleton fossil have changed everything we know about the origins of modern birds.
Each of the 11,000 species of birds known to us today is classified under one of two groups, based on the arrangement of their palette bones - Ostriches, emus and their relatives are classified under the "ancient jaw" group, characterised by a fused beak and all others are classified under the "modern jaw" group with a mobile, dexterous beak.
The fossil was found in a limestone quarry near the Belgian- Dutch border in the 1990s and was first studied in the early 2000s. Twenty years after its discovery, the fossil was loaned to Dr. Field's group in Cambridge who were able to examine it closely using CT scans.
Researchers identified bones from the roof of the mouth of a species of large ancient bird, which they have named Janavis feinalidens. On closer examination, they recalled that they had seen a similar bone before in a turkey skull. When the two were compared side by side, they were identical, leading scientists to conclude that the unfused jaw condition, which turkeys share, evolved before the fused jaw condition of ostriches and their relatives.
Researchers have said that the fused palates must have evolved at some point after modern birds were already established, for unknown reasons.