21 in the journal Communications Biology. "So all in all, this study provides an example on how climate change at the end of the last ice age could have led to the formation of new subspecies," he said. As the environment changed, however, the horned lark diverged into the two evolutionary lineages that exist today, Dalén said. It appears that the newly discovered bird is an "ancestor of two different subspecies of horned lark," he said. Nowadays, there are two subspecies of horned lark: "one living on the tundra in the far north of Eurasia and the other in the steppe in the south, in Mongolia and its neighboring countries," Dalén said. When the last ice age ended about 11,700 years ago, the mammoth steppe transitioned into the three main Eurasian environments that exist today: the northern tundra, the taiga (a coniferous forest) in the middle, and the steppe in the south, said Dalén, the senior researcher on the new study. When this bird was alive, the land was a mix of steppe (unforested grassland) and tundra (treeless, frozen ground), according to pollen records from 50,000 to 30,000 years ago. This discovery sheds light on the transformation of the so-called mammoth steppe. The results revealed that the ice age bird was a female horned lark ( Eremophila alpestris). Then, the scientists took the finished mitochondrial DNA puzzle and searched for a match in an online database that has the genetic sequences of nearly every bird alive today. Although the bird's mitochondrial DNA was fragmentary - there were "many millions of short DNA sequences," Dalén said, a common occurrence in ancient specimens - the team was able to piece together these short sequences with the help of a computer program. To discover the bird's species, the researchers sequenced its mitochondrial DNA, genetic data that is passed down through the maternal line. Radiocarbon dating revealed that the bird lived during the same time as other ice age beasts, including mammoths, horses, woolly rhinos, bison and lynx. In this slideshow, youll find pictures and detailed profiles of over 50 prehistoric and recently extinct birds, ranging from Archaeopteryx to the Passenger Pigeon. He brought the ice age samples to his lab, where postdoctoral researcher Nicolas Dussex, the lead author of a new study on the bird, analyzed the remains. The first true birds evolved during the late Jurassic period, and went on to become one of the most successful and diverse branches of vertebrate life on earth. So, Dalén "collected a couple of feathers and a small piece of tissue for radiocarbon dating and DNA sequencing," he said. When the fossil hunters first uncovered the bird in September 2018, Dalén and his colleagues had no idea of the mystery bird's age or species. “The two female bones were similar in size to the other bones in their sample, which tends to refute an earlier idea that male and female dodo were very different in adult size.The 46,000-year-old bird's delicate feet are still in good shape. “It’s very cool that the team was able to identify two individuals in their sample as laying females,” says Helen James, curator of birds at the Smithsonian National Museum of Natural History in Washington DC. These bones contained a supplementary tissue called medullary bone, which is a vital source of calcium when making egg shells, and is unique to females. The team even identified two bones as female. And some report dodos covered with real feathers, probably corresponding to birds that had completed the cycle,” says Angst. Some describe a mix of downy plumage and real feathers. “Some report downy black plumage, probably at the beginning of moulting. “To produce new feathers, the birds need extra calcium, and the cavities show they were extracting it from the bones,” says Angst.Įstablishing that the birds had a moulting cycle also helps to explain why sailors visiting Mauritius often differed in their descriptions of dodos. Other bones had large cavities that corresponded with the moulting cycle. Some of the dodos were juveniles: their bones were unusually rich in fibrolamellar bone, which contains many immature bone cells that can be rapidly deposited, allowing the bird to grow quickly. With one exception, all the bones were from the hind legs. Angst and her colleagues worked out the cycle by analysing the structure and composition of 22 bones from 22 dodos.
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