Identify the ancient bird with legs longer than the lower legs. Researchers discovered a bird in the foot from 99 million years ago to be preserved in amber that had a late-toe extremity. The study, published in the journal Current Biology on July 11, indicates that this bird can use fingers to hook the food from the truck trees. This is the first time such a foot structure is observed in birds, either extinct or alive.
"I was surprised when I saw the amber," says the first author Lida Xing at the China University of Geosciences (Beijing). "It shows that ancient birds were much different from what we thought. They have changed many different features to suit their surroundings."
To study the fossil of the Cretaceous period, Xing and his colleagues started amber using the micro-CT and created 3D rebuilding feet. They found that the bird's third finger, measuring 9.8 millimeters, is 41percent longer than the second toe and 20 percent longer than its tarsometatarsus, which is a bone in the lower legs of the birds. The team compared the ratios to about 20 other dead birds from the same time and 62 live birds. There is no bird with one foot resembling this one.
The bird was fossilized in amber 99 million years ago. (Lida Xing / Current Biology )
The researchers named it Elektorornis chenguangi. Elektorornis means "amber bird," and it belongs to a group of dead birds called Enantiornithes, the most fertile bird species known from the Mesozoic era. It was thought that the Enantiornitines had been dead during Cretaceous-Paleogene's destruction about 66 million years ago, including dinosaurs. They have no living descendants. Based on fossil, the team estimates that Elektorornis is smaller than a sparrow, and it is arboreal, meaning it spends most of its time on trees compared to soil or water.
"The upper limbs are something you can usually find in arboreal animals because they need to handle these branches and lay their fingers around them," says co-author Jingmai O & # 39; Connor in the Chinese Academy of Sciences. "But the excessive difference in the length of the toe, as we know it, has never seen before."
Tarsal Structure and Integumentary Structures Preserved in Elektorornis chenguangi HPG-15-2.  (Lida Xing / Current Biology )
The amber foot is located at, measuring 3.5 centimeters and weighing 5.5 grams, was discovered around 2014 Burma Valley of Myanmar. During the Mesozoic period, the valley is full of sapling trees, a sticky substance that appears on the bark of the ship. Plants and small animals, such as geckos and spiders, are often trapped in resin and fossilized into amber after millions of years. Scientists have discovered many dead animals, including the oldest known bee and a feathered dinosaur tail, in the amber from this valley.
Xing took the amber from a local amber businessman, who does not know what animal this strange foot is.
"Some merchants thought it was a leg of lizard, because the lizards had long legs," says Xing. "Even though I did not see a bird's nail that looked like this before, I knew it was a bird. Like most birds, this foot has four toes, while the five have strings . "
It remains unknown to why amber birds have changed as unusual properties. The only known animal with an invalid length number is the bee. Aye-aye is a lemur that uses its long central fingers to practice larvae and insects from tree trees for food. Therefore, researchers suggest that Elektorornis can use its finger for the same purpose.
"This is the best guess we have," says O & # 39; Connor. "There is no bird with a similar morphology that can be considered a modern analog for this fossil bird. Many ancient birds are likely to produce absolutely different things than live birds. The fossil reveals different ecological niches that ancient birds experimented as they grow. "
Moving forward, the team expects to take proteins and pigments from their feathers exposed on the amber surface. Xing said that this data will help them better understand the adaptation of birds to the environment, as if they were plumage.
Top image: The artist's impression of a bird with a third finger 41 percent longer than the second finger. Source: Zhongda Zhang / Current Biology
The article, originally titled, "The bird with unusual toe fossils found in amber" was first published in the Science Daily .
Source: Cell Press. "Birds with unusual fingers are found fossilized in amber." ScienceDaily. ScienceDaily, July 11, 2019. www.sciencedaily.com/releases/2019/07/190711141407.htm
Lida Xing, Jingmai K. O & # 39; Connor, Luis M. Chiappe, Ryan C. McKellar, Nathan Carroll, Han Hu, Ming Bai, Fuming Lei. A New Enantiornithine Bird with Unusual Pedal Equally Found in Amber . Current Biology 2019; DOI: 10.1016 / j.cub.2019.05.077