Our lower jaw moves as we chew food. The upper jaw is completely immobile and fully fused with our skull. However, some contemporary birds, such as chickens and ducks, can also move their upper jaw. Such a mouth is functional because the birds can perform some fairly dexterous tasks with it.
The capacity to move both jaws was very recently acquired by ‘neognaths,’ or birds, according to general consensus in evolutionary theory. But a CT scan of a toothed bird fossil has upended this thinking.
This bird was alive right before an asteroid killed out all non-avian dinosaurs, 66.7 million years ago. Researchers have revealed that this bird, Janavis finalidens, was able to move both its jaws.
This has provided evidence to researchers that ability to move both jaws predated advent of modern birds.
‘The assumption has always been … that the ancestral condition for all modern birds was this fused-up condition typified by ostriches and their relatives just because it seems simpler and more reminiscent of non-bird reptiles,’said Dr Daniel Field, senior author of the research from the University of Cambridge. He was quoted by The Guardian.
The research has been published in scientific journal Nature.
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