Ancient Bird Crops
A new discovery by researchers from KU and China pushes back by millions of years proof that birds¹ digestive systems have ancient origins.
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Investigators advance the understanding of bird evolution by finding ancient fossil crops. From the University of Kansas, this is Research Matters. I’m Brendan Lynch.
A crop is a muscular pocket in the esophagus that most modern birds use to store and soften seeds. Larry Martin and colleagues from KU and China have found fossil evidence of a crop in two avian species from about 130 million years ago. Their discovery recently was published in the Proceedings of the National Academy of Sciences.
Martin: We think that perhaps the development of a gizzard and a crop are specialization for eating seeds, and it was eating seeds that may have been one of the great motivations for birds to lose their teeth. It shows that seed eating was an important driving force in the early diversification and radiation of modern-type birds.
According to Martin, the crop is an important clue to how birds evolved from the Mesozoic era, when the vast majority had teeth, to modern bird species that lack them.
Martin: These animals that we’ve found that have crops and gizzards are also among the few Mesozoic birds that show a loss of teeth.
Of the two species found to have crops, Martin said that one belonged to a long-extinct evolutionary side-branch, while the other was a relative of modern birds.
Martin: Sapeornis was a pretty fair-sized bird, about the size of an ordinary chicken. It belongs to a group of basal birds that are related to, but actually separate from, the line that leads to modern birds. The other bird that we have, Hongshanornis, is essentially a modern bird, but an awfully old one — one of the oldest modern birds.
For more on ancient bird cops, log on to Research Matters dot KU dot EDU. For the University of Kansas, I’m Brendan Lynch.
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Researchers advance understanding of bird evolution by finding fossil crops