Spring Break
Ancient fossils offer insight into bird evolution
Issue date: 10/2/08
A 50-million-year-old skull of an ancient goose discovered in England is giving new insight into a unique ancient line of birds.
The skull, discovered on the Isle of Sheppey off the coast of England, had one very unusual attribute: its beak was lined with bony teeth.
The bird, which has been assigned to the extinct species Dasornis emuinus, had a 16-foot wingspan and resembled an albatross more than a goose.
While paleontologists have discovered other fossils of bony-toothed birds, this new fossil is the first substantial skull of a very large Paleogene, an ancient bony-toothed bird.
It is one of the most well-preserved specimens ever found in the London Clay deposits, which surround much of London, Essex and northern Kent in southeast England.
Like modern birds, the new fossil specimen had a beak made of keratin, the same protein that forms fingernails and hair in humans and other mammals.
Teeth have actually arisen twice in the bird lineage. While all birds lost their true teeth over 100 million years ago, Dasornis and other bony-toothed birds known as pelagornithids re-evolved pseudo-teeth made of the same keratin protein as the beak.
While the pseudo-teeth were not preserved in the fossilization process, two pits which would accommodate teeth were observed.
Ancestors of modern birds may have lost their teeth in order to save weight, making flying easier, but Dasornis re-evolved teeth for dietary reasons.
Much like modern-day albatrosses and geese, Dasornis likely skimmed the water's surface to catch fish or other aquatic animals for food.
The pseudo-teeth would have allowed the ancient bird to maintain a tight hold on its prey, preventing the meal from slipping away.
These findings have been described in the Sept. 26 edition of the journal Paleontology.
The skull, discovered on the Isle of Sheppey off the coast of England, had one very unusual attribute: its beak was lined with bony teeth.
The bird, which has been assigned to the extinct species Dasornis emuinus, had a 16-foot wingspan and resembled an albatross more than a goose.
While paleontologists have discovered other fossils of bony-toothed birds, this new fossil is the first substantial skull of a very large Paleogene, an ancient bony-toothed bird.
It is one of the most well-preserved specimens ever found in the London Clay deposits, which surround much of London, Essex and northern Kent in southeast England.
Like modern birds, the new fossil specimen had a beak made of keratin, the same protein that forms fingernails and hair in humans and other mammals.
Teeth have actually arisen twice in the bird lineage. While all birds lost their true teeth over 100 million years ago, Dasornis and other bony-toothed birds known as pelagornithids re-evolved pseudo-teeth made of the same keratin protein as the beak.
While the pseudo-teeth were not preserved in the fossilization process, two pits which would accommodate teeth were observed.
Ancestors of modern birds may have lost their teeth in order to save weight, making flying easier, but Dasornis re-evolved teeth for dietary reasons.
Much like modern-day albatrosses and geese, Dasornis likely skimmed the water's surface to catch fish or other aquatic animals for food.
The pseudo-teeth would have allowed the ancient bird to maintain a tight hold on its prey, preventing the meal from slipping away.
These findings have been described in the Sept. 26 edition of the journal Paleontology.
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