Meet the ancient bird that had tears longer than its lower legs. Scientists have discovered a bird's foot from 99 million years ago preserved in amber that had a hyper-longed third toe. The study, published in the newspaper Current Biology on July 1
"I was very surprised when I saw the yellow," says first author Lida Xing of China's University of Earth Sciences (Beijing). "It shows that old birds were far more versatile than we thought. They had developed many different functions to adapt to their environments."
To study the waterfall in Crete, Xing and his colleagues scanned the yellow with micro-CT and created a 3-D reconstruction of the foot. They found that the bird's third toe, measuring 9.8 millimeters, is 41 percent longer than its second toe and 20 percent longer than its tarsometatarsus, which is a bone in the lower legs of the birds. The team compared the conditions with the 20 other extinct birds from the same era and 62 live birds. No bird has a foot similar to this one.
The researchers are called Elektorornis chenguangi. Elektorornis means "yellow bird" and it belongs to a group of extinct birds called Enantiornithes, the most abundant type of bird known from the Mesozoic era. It is believed that Enantiornithines were eradicated during the Cretaceous-Paleogen extermination event about 66 million years ago along with dinosaurs. They have no living descendants.
Based on the fossil, the team estimates that Elektorornis was smaller than a sparrow, and it was arboreal, which meant that it spent mostly time in trees as opposed to on land or in water.
"Long toes are something you usually see in farm animals, because they must be able to seize these branches and put their toes around them," says co-author Jingmai O & # 39; Connor of the Chinese Academy of Sciences. "But this extreme difference in toe lengths, as far as we know, has never seen before."
The yellow foot was found, measuring 3.5 centimeters long and weighing 5.5 grams, discovered around 2014 in the Hukawng Valley of Myanmar. During the Mesozoic era, the valley was full of trees that produced resin, a sticky substance that oozes out of the tree bark. Plants and small animals, such as cucumbers and spiders, are often trapped in the resin and become fossilized with amber after millions of years. Scientists have discovered many extinct animals, including the oldest known bee and a distant dinosaur neck, in amber from this valley.
Xing received amber from a local amber dealer who did not know which animal this strange foot belonged to.
"Some traders thought it was a lizard foot, because lizards tend to have long toes," Xing says. "Although I have never seen a bird claw look like this, I know it's a bird. Like most birds, this foot has four toes, while lizards have five."
It is still unknown why the yellow bird developed such an unusual property. The only known animal with disproportionate numbers is aye-aye. Aye-aye is a lemur that uses its long middle finger to fish larvae and insects from tree trunks for food. Therefore, the researchers suggest that Elektorornis may have used the toe for the same purpose.
"This is the best guess we have," says O & # 39; Connor. "There is no bird with similar morphology that can be considered a modern analog for this fossil bird. A lot of ancient birds probably did completely different things than living birds. This fossil exposes another ecological niche that these early birds experimented with as they developed. Hope forward, the team hopes to extract the proteins and pigments from some feathers exposed on the surface of yellow. Xing says that such data can help them better understand the bird's adaptation to the environment, for example, if it had camouflage depth.
Mummified old bird offers clues about flying during middle cruises
Current biology Xing et al. "A new enantiornitine bird with unusual pedal proportions found in amber" https://www.cell.com/current-biology/fulltext/S0960 – 9822 (19) 30691-8, DOI: 10,1016 / j. Cub.2019.05.077
Bird with unusually long toes found fossil in amber (2019, July 11)
July 11, 2019
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