By Stephen Beech via SWNS
A “weird” early species of bird with “incredibly strong” teeth actually ate fruit rather than flesh, according to a new study.
Fossilized seeds have been found in the stomach of Longipteryx chaoyangensis which lived 120 million years ago in what is now north eastern China.
Paleontologists say the discovery shows that the birds were eating fruits, despite a long-standing hypothesis that they feasted on fish or insects.
Study lead author Dry Jingmai O’Connor, associate curator of fossil reptiles at the Field Museum in Chicago, said: “Longipteryx is one of my favorite fossil birds, because it’s just so weird.
“It has this long skull, and teeth only at the tip of its beak.”
Study co-author Alex Clark, a PhD student at the Field Museum and the University of Chicago, said: “Tooth enamel is the hardest substance in the body, and Longipteryx’s tooth enamel is 50 microns thick.
“That’s the same thickness of the enamel on enormous predatory dinosaurs like Allosaurus that weighed 4,000 pounds, but Longipteryx is the size of a blue jay,”
Longipteryx was discovered in 2000, and at the time, scientists suggested that its kingfisher-like elongated skull meant that it hunted fish.
However, that idea has been challenged by a number of scientists, including Dr. O’Connor.
She said: “There are other fossil birds, like Yanornis, that ate fish, and we know because specimens have been found with preserved stomach contents, and fish tend to preserve well.
“Plus, these fish-eating birds had lots of teeth, all the way along their beaks, unlike how Longipteryx only has teeth at the very tip of its beak. It just didn’t add up.”
But, until now, no specimens of Longipteryx had been found with fossilized food still in their stomachs for scientists to confirm what it ate.
Dr. O’Connor visited the Shandong Tianyu Museum of Nature in China, where she noticed two Longipteryx specimens that appeared to have something in their stomachs.
She consulted with her colleague, palaeobotanist and Field Museum associate curator of fossil plants Fabiany Herrera, who was able to determine that the tiny, round structures in the birds’ stomachs were seeds from the fruits of an ancient tree.
The trees that Longipteryx was feeding from were gymnosperms, relatives of today’s conifers and gingkos.
Dr. O’Connor said that since Longipteryx lived in a temperate climate, it probably wasn’t eating fruits year-round.
She and her colleagues suspect that it had a mixed diet which included insects when fruits weren’t available.
Dr. O’Connor says that Longipteryx is part of a larger group of prehistoric birds called the enantiornithines, and the new discovery marks the first time that scientists have found any stomach contents from an enantiornithine in China’s Jehol Biota despite thousands of uncovered fossils.
She said: “It’s always been weird that we didn’t know what they were eating, but this study also hints at a bigger picture problem in paleontology, that physical characteristics of a fossil don’t always tell the whole story about what animal ate or how it lived.”
The researchers believe the bird’s strong teeth were used as a weapon for fighting
Clark said: “The thick enamel is overpowered, it seems to be weaponized.
“One of the most common parts of the skeleton that birds use for aggressive displays is the rostrum, the beak.
“Having a weaponized beak makes sense, because it moves the weapon further away from the rest of the body, to prevent injury.”
Dr. O’Connor said: “There are no modern birds with teeth, but there are these really cool little hummingbirds that have keratinous projections near the tip of the rostrum that resemble what you see in Longipteryx, and they use them as weapons to fight each other.
She says weaponized beaks in hummingbirds have evolved at least seven times, allowing them to compete for limited resources.
Clark suggested the hypothesis that perhaps Longipteryx’s teeth and beak also served as a weapon, perhaps evolving under social or sexual selection.
The researchers, whose findings were published in the journal Current Biology, say that beyond figuring out more about the life of the prehistoric bird, they hope their research helps illuminate broader questions in paleontology about how much scientists can trust skeletal traits to tell the story of animal behavior.
Dr. O’Connor added: “We’re trying to open up a new area of research for these early birds and get paleontologists to look at these structures, like the beak, and think about the complexity of the behaviors that these animals might have engaged in beyond just what they were eating.
“There are many factors that could be shaping the structures that we see.”
