lpetrich
Contributor
Present-day birds are well-known for having beaks and having no teeth. "Hen's teeth" are something proverbially nonexistent. But their dinosaurian ancestors and close relatives of ancestors all had teeth. So how did they lose their teeth and grow beaks instead?
How Did Birds Lose Their Teeth And Get Their Beaks? Study Offers Clues : The Two-Way : NPR, Fossils reveal how ancient birds got their beaks | Science | AAAS Around 100 million years ago, there was a seaway in the middle of North America. On the shores of that seaway lived an early bird called Ichthyornis dispar. It looked much like a present-day seagull and likely behaved like one, but its long snout of a mouth had teeth.
A team at Yale recently did some CT scans of some Ichthyornis skulls, finding that these birds had small hooked beaks on the front ends of their snouts. This pointed to a path for loss of teeth: the beak growing bigger and bigger and fewer and fewer teeth growing, until the bird was toothless.
Ichthyornis also had another feature of present-day birds: a movable upper jaw.
A new Lower Cretaceous bird from China and tooth reduction in early avian evolution | Proceedings of the Royal Society of London B: Biological Sciences: Zhongjianornis yangi, the first known toothless bird. However, the authors of that paper consider it a separate loss of teeth from present-day birds' ancestors, and they propose that Cretaceous birds lost their teeth several times.
Discovery of an ornithurine bird and its implication for Early Cretaceous avian radiation | PNAS: Hongshanornis longicresta with reduced teeth and a beak on both jaws. Ornithurines ("bird tails") -- birds like Ichthyornis and present-day birds. Though Archaeopteryx had a long tail, like most (non-avian) dinosaurs, present-day birds and some Cretaceous ones had short tails.
How Did Birds Lose Their Teeth And Get Their Beaks? Study Offers Clues : The Two-Way : NPR, Fossils reveal how ancient birds got their beaks | Science | AAAS Around 100 million years ago, there was a seaway in the middle of North America. On the shores of that seaway lived an early bird called Ichthyornis dispar. It looked much like a present-day seagull and likely behaved like one, but its long snout of a mouth had teeth.
A team at Yale recently did some CT scans of some Ichthyornis skulls, finding that these birds had small hooked beaks on the front ends of their snouts. This pointed to a path for loss of teeth: the beak growing bigger and bigger and fewer and fewer teeth growing, until the bird was toothless.
Ichthyornis also had another feature of present-day birds: a movable upper jaw.
A new Lower Cretaceous bird from China and tooth reduction in early avian evolution | Proceedings of the Royal Society of London B: Biological Sciences: Zhongjianornis yangi, the first known toothless bird. However, the authors of that paper consider it a separate loss of teeth from present-day birds' ancestors, and they propose that Cretaceous birds lost their teeth several times.
Discovery of an ornithurine bird and its implication for Early Cretaceous avian radiation | PNAS: Hongshanornis longicresta with reduced teeth and a beak on both jaws. Ornithurines ("bird tails") -- birds like Ichthyornis and present-day birds. Though Archaeopteryx had a long tail, like most (non-avian) dinosaurs, present-day birds and some Cretaceous ones had short tails.
