Friday, June 30, 2017

Which extinct ducks could fly?


Copied from Science Daily, early bird news


Which extinct ducks could fly?

Date: June 7, 2017

Source:

American Ornithological Society Publications Office

We're all familiar with flightless birds: ostriches, emus, penguins -- and ducks? Ducks and geese, part of a bird family called the anatids, have been especially prone to becoming flightless over the course of evolutionary history. However, it can be difficult to determine from fossils whether an extinct anatid species could fly or not. A new study from The Auk: Ornithological Advances takes a fresh approach, classifying species as flightless or not based on how far their skeletal proportions deviate from the expected anatomy of a flying bird and offering a glimpse into the lives of these extinct waterfowl.



Fossils such as this partial skeleton of a Hawaiian species called Ptaiochen pau were used to determine whether extinct ducks and geese could fly.

Kyoto University's Junya Watanabe painstakingly measured 787 individual birds representing 103 modern duck and goose species. From this data, he developed a mathematical model that was able to separate flightless and flying species based on their wing and leg bones -- flightless species, the math confirmed, have relatively small wings and relatively large legs. Applying the model to fossil specimens from 16 extinct species identified 5 of the species as flightless, ranging from a land-dwelling duck from New Zealand to a South American duck that propelled itself underwater with its feet.

"I really enjoyed measuring bones in museums and appreciate the hospitality given to me by museum staff. One of the most exciting things was to find interesting fossils that were previously unidentified in museum drawers," says Watanabe. "What is interesting in fossil flightless anatids is their great diversity; they inhabited remote islands and continental margins, some of them were specialized for underwater diving and others for grazing, and some were rather gigantic while others were diminutive."

"Dr. Watanabe has developed a valuable statistical tool for evaluating whether a bird was capable of powered flight or not, based on measurements of the lengths of only four different long bones. His method at present applies to waterfowl, but it could be extended to other bird groups like the rails," according to Helen James, Curator of Birds at the Smithsonian Institution's National Museum of Natural History. "Other researchers will appreciate that he offers a way to assess limb proportions even in fossil species where the bones of individual birds have become disassociated from each other. Disassociation of skeletons in fossil sites has been a persistent barrier to these types of sophisticated statistical analyses, and Dr. Watanabe has taken an important step towards overcoming that problem."

Saturday, June 10, 2017

Stunning fossil reveals prehistoric baby bird caught in amber


Stunning fossil reveals prehistoric baby bird caught in amber

Copied to this blog from the Washington Post

By Ben Guarino June 9 at 6:00 AM 

Amber hunters in Burma dug up a remarkably complete bird hatchling that dates to the time of the dinosaurs. The bird's side, almost half of its body, was dipped in tree sap, which hardened around the neck bones, claws, a wing and its toothed jaws.

Scientists identified the animal as a member of the extinct group called enantiornithes, and published their discovery in the journal Gondwana Research this week.

The chick died young and fell into a pool of sap. It died halfway through its first feather molt, suggesting that the animal broke out of its egg just a few days before it perished. Its life began in the moist tropics beneath conifer trees. It ended near a puddle of conifer gunk, called resin, which fossilized into amber. Burmese diggers uncovered the amber 99 million years later.

The whole specimen is trapped in amber. (Lida Xing)

“Enantiornithines are close relatives to modern birds, and in general, they would have looked very similar. However, this group of birds still had teeth and claws on their wings,” said Ryan McKellar, a paleontologist at Canada's Royal Saskatchewan Museum. This animal lived during the Cretaceous Period, which came to a cataclysmic close 65.5 million years ago and took the non-bird dinosaurs with it.

The enantiornithes, due to their distinct hip and ankle bones, may have flown differently than modern birds. But they were capable fliers. (If you are wondering whether this bird relative was more bird or winged dinosaur, well, consider it both: Birds are avian dinosaurs, after all.)

Entombed in amber were details as fine as the hatchling's eyelid and the outer opening of its ear. The resin recorded no sign of a struggle. “The hatchling may have been dead by the time it entered” the resin pool, McKellar said. “One of the leg bones has been dragged away from its natural position, suggesting that the corpse may have been scavenged before it was covered by the next flow of resin.”

Evidence suggests that enantiornithes received little in the way of parental care, unlike more doting modern birds. The ancient chicks, born on the ground, had to scamper into trees to avoid being eaten. Scampering enantiornithes got stuck in resin fairly frequently, McKellar said, though this fossil is far more comprehensive than typical specimens.

Its 99-million-year-old claws appear almost as detailed as chicken feet you'd find in a supermarket. The foot, presumed at first to be a lizard's by the amber miner who found it, was covered in golden scales and just under an inch long. “The preserved skin surface allows us to observe the feet in great detail,” McKellar said.

The resin trapped one of the bird's wings as well. Despite its young age, the animal already had brown flight feathers on its wings. McKellar said it also had “a sparse coat of fluffy pale or white feathers across most of its belly, legs, and tail.”

McKellar and his colleagues probed the fossil using several types of imaging technology, including light microscopes and X-ray micro-CT scanning. The researchers discovered that the feathers on the enantiornithes' wings were quite similar to modern bird feathers. But its tail and legs were covered by what McKellar described as tufts similar to “proto-feathers” or “dino-fuzz.”

Recent amber discoveries offer strikingly detailed, if orange-tinted, windows into ancient worlds. Sap trapped not only birds but lizards, bugs and bits of non-bird dinosaurs, too. In December, McKellar and his colleagues announced they'd found a dinosaur tail trapped in amber also excavated from a mine in Burma (also known as Myanmar).

But amber containing dino DNA, as popularized by “Jurassic Park” and its ancient mosquitoes swollen with dinosaur blood, appears to remain in the realm of science fiction. “Unfortunately, DNA seems to be ‘off the menu’ for specimens such as this one,” McKellar said. “To the best of our current understanding, DNA has a half-life of around 500 years and cannot be recovered in meaningful quantities from amber pieces that are more than a few million years old.”

That doesn't mean amber completely erases prehistoric biochemistry. The scientists have teased iron from the toothed bird, trapped in carbon in the hatchling's soft tissues, possibly from its blood. Further research may uncover proteins from the bird's feathers, McKellar said, allowing experts to home in on the colors of the animal's brown plumage.