More evidence of bird evolution.

[shunyadragon]

Source: https://www.scientificamerican.com/article/smallest-known-dinosaur-found-in-amber/

Smallest Known Dinosaur Found in Amber

A bird skull from Myanmar hints at a lost world of tiny fossils that are waiting to be unearthed

By Riley Black on March 11, 2020

The word “dinosaurs” conjures up images of fierce and enormous reptiles. But not all of the “terrible lizards” were huge. Part of their success rested on the fact that they came in all shapes and sizes. And now paleontologists have revealed what may be the smallest dinosaur of all time.

Described by China University of Geosciences paleontologist Lida Xing and his colleagues in a study published Wednesday in Nature, the 99-million-year-old fossil was found in Myanmar and is part of a growing number of amber-bound windows into the Mesozoic world. Paleontologists working in the Southeast Asian country have in recent years encountered dinosaur tails, baby birds, new insect species and even seagoing creatures that became enclosed in gobs of sticky sap. What makes this latest find stand out, however, is just how tiny it is.

The newly discovered dinosaur, preserved within hardened resin during the Mid-Cretaceous period of the Mesozoic era, is represented by nothing more than a skull. From its tiny teeth to the delicate ringed bones of its eyes, it only measures about half an inch long. But even though amber-encased fossils are sometimes difficult to study—given that researchers must rely on imaging techniques to slice through the layers of resin—it is apparent that this little creature was a toothed bird that lived during the reign of its dinosaurian kin. Xing and his co-authors have named it Oculudentavis khaungraae—with the genus being derived from “toothed eye bird” in Latin and the species being designated in honor of fossil collector Khaung Ra, who donated the item for study.

Artistic rendering of Oculudentavis that imagines what it looked like while preying on an insect. Credit: Han Zhixin
Precisely where Oculudentavis belongs on the bird family tree is not quite clear. It appears to be a relatively archaic form that paleontologists call a stem bird—a bird close to the point at which avians split from their feathered dinosaur ancestors. Then again, additional analyses or fossil finds might change which branch it is placed on. Although Oculudentavis really does seem to be a bird, says Bruce Museum paleontologist Daniel Ksepka, “I would be unsurprised if it turned out to fall somewhere else in the bird part of the dinosaur family tree.” (Ksepka was not involved in the new paper.)

What most excited study co-author Lars Schmitz, a paleontologist at Claremont McKenna, Scripps and Pitzer colleges, were the tiny animal’s eyes. “I must say the scleral ring of Oculudentavis is just great,” Schmitz says, noting that the thin, delicate bones of each eye are in place and only slightly deformed through fossilization. The arrangement of these bones can say something about when Oculudentavis was active. “The individual bones of the ring have an odd lizardlike shape. And the proportional size of the opening where the pupil would have been suggests daytime activity,” Schmitz says.

In life, Oculudentavis would have been about the size of a small hummingbird. This stature makes it the tiniest Mesozoic dinosaur yet discovered, significantly smaller than other contenders for the title, such as Fruitadens in Colorado. And identifying small species has a big influence on how paleontologists reconstruct the past.

Large dinosaurs were some of the first to be discovered and attain fame. Not only did such species have sturdy bones capable of withstanding the violence of decay and preservation, but (during the early 20th century in particular) museums and paleontologists intentionally looked for big, imposing animals that would help build careers and drive exhibit attendance. Scientific infatuation with larger dinosaurs was so great that informative and important skeletons were sometimes “headhunted,” because collecting impressive skulls was seen as more critical for building collections. But miniature species were historically ignored by fossil hunters, meaning that there are undoubtedly small species waiting to be found.

Along with discoveries in other localities—such as the fossil beds of Liaoning province in China, which have yielded dozens of exquisite specimens—Oculudentavis and additional finds in Myanmar’s amber have started to put together a view of the dinosaurian world that differs from what has been assembled from classic spots in the American west. And the new find is relevant to the range of sizes birds took through time. “I was amazed by how small this fossil was,” Ksepka says. A better body fossil is needed, to be sure, but Oculudentavis might be smaller than even the tiniest modern hummingbirds. If that possibility turns out to be the case, Ksepka notes, it would mean the largest and smallest birds of all time are extinct.

More finds like Oculudentavis will probably follow it. “We are currently only capturing a small fraction of the small end of the size spectrum, with an incomplete picture of the biodiversity in the age of dinosaurs,” Schmitz says. Even in relatively familiar fossil-producing spots, the most likely candidates for new species are going to be comparatively tiny. These animals are just as important as the hulking mountains of bone that fill museum halls. They are the threads that helped form the ecosystems beneath the feet of giants.

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Oldest known bird fossil discovered 67 million years old,

Source: https://www.bbc.com/news/science-environment-51925335

Fossil 'wonderchicken' could be earliest known fowl

By Helen Briggs
BBC News

A newly discovered fossil bird could be the earliest known ancestor of every chicken on the planet.

Living just before the asteroid strike that wiped out giant dinosaurs, the unique fossil, from about 67 million years ago, gives a glimpse into the dawn of modern birds.

Birds are descended from dinosaurs, but precisely when they evolved into birds like the ones alive today has been difficult to answer.

This is due to a lack of fossil data.

The newly discovered - and well-preserved - fossil skull should help fill in some of the gaps.

"This is a unique specimen: we've been calling it the 'wonderchicken'," said Dr Daniel Field of the University of Cambridge.

"It's the only nearly complete skull of a modern bird that we have, so far, from the age of dinosaurs and it's able to tell us quite a lot about the early evolutionary history of birds."

The fossil bird has been named Asteriornis maastrichtensis, after Asteria, a Greek goddess of falling stars who turns into a quail. It was found in a quarry on the Netherlands-Belgium border.

The bird weighed in at just under 400g and was an early member of the group that gave rise to modern-day chickens, ducks and other poultry.

At the time, the region was covered by a shallow sea, and conditions were similar to modern tropical beaches. With its long, slender legs, the bird may have been a shore dweller.

"Birds are such a conspicuous and important group of living animals, being able to say something new about how modern birds actually arose is really a significant thing for palaeontologists and evolutionary biologists," said Dr Field.

"The wonderchicken is going to rank as a truly important fossil for helping clarify the factors that actually gave rise to modern birds."

The research is published in the journal Nature.

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A new early important transitional species between raptors and birds.

Source: https://phys.org/news/2020-06-argentine-paleontologists-small-carnivorous-dinosaur.html

Argentine paleontologists discover small carnivorous dinosaur


[IMG]
The fossilized jaw of an Overoraptor chimentoi, a new species of dinosaur discovered in Argentine Patagonia
Fossilized remains of a new species of dinosaur that lived 90 million years ago have been discovered in Patagonia, Argentine paleontologists announced on Thursday.

The winged dinosaur had legs similar to the velociraptor and experts believe it may hold the key to revealing information about the evolution of birds.

The fossil remains, which measure less than a meter and a half in length, were discovered at a dig in the province of Rio Negro in Argentine Patagonia, around 1,100 kilometers (685 miles) from Buenos Aires, the scientific dissemination agency from the La Matanza university said.

It is a new species of carnivorous Paraves theropod that has been named Overoraptor chimentoi, explained Matias Motta, a researcher from the Argentine natural sciences museum.

It is related to another species found more than 10,000 kilometers away in Madagascar.

The first remains were discovered in 2013, with more fossils found in a second dig in 2018.

"This animal had a very sharp claw on its index toe, which certainly was used to attack prey, and it had a long and graceful leg, which indicates it was a running animal," said Motta, the main author of the study published in The Science of Nature magazine.

"It was certainly fast, agile and, like all its relatives, it would have been carnivorous."

Researchers were surprised to find that while its legs were similar to the "raptor" family of dinosaurs, its upper limbs were very long and robust, similar to modern birds.

The second dig uncovered many bones, including an almost complete foot, tail vertebrae and parts of a wing, said paleontologist Federico Brisson Egli.

Previous discoveries in Patagonia of dinosaurs with bird-like features belonged to the Unenlagia genus of dromaeosaurid theropods, which were agile and walked on their hind legs.

"Contrary to what we originally assumed, the Overoraptor is not part of the Unenlagia family, but from another group including a Madagascan species called Rahonavis," said paleontologist Fernando Novas.

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One point that this reference did not make clear, which is an important factor that makes this discovery very important is that the Ravenavis family this species is an older primitive missing link that is more closely related to Avialae the family that birds more directly descended from. Both Unenlagia and the Ravenavis families of Therapod dinosaurs and had feathered bied like dinosaurs. There are not many fossils of species from Ravenavis family. In fact I believe the only other species in this family is found in Madagascar.

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More recent analysis of an older unique discovery of a bird-like dinosaur reveals evidence of a more continuum of evolution from dinosaurs to birds.

One-of-a-Kind Dinosaur Specimen Discovered in China Offers View Into Dinosaur-Bird Evolution

TOPICS:BirdsDinosaursEvolutionPaleontologyPopularS an Diego Natural History Museum
By SAN DIEGO NATURAL HISTORY MUSEUM JANUARY 19, 2020

San Diego Natural History Museum paleontologist describes a dinosaur that is new to science, shows dinosaurs grew up differently from birds.

A new species of feathered dinosaur has been discovered in China, and described by American and Chinese authors in the journal, The Anatomical Record.

The one-of-a-kind specimen offers a window into what the earth was like 120 million years ago. The fossil preserves feathers and bones that provide new information about how dinosaurs grew and how they differed from birds.

“The new dinosaur fits in with an incredible radiation of feathered, winged animals that are closely related to the origin of birds,” said Dr. Ashley Poust, who analyzed the specimen while he was a student at Montana State University and during his time as a Ph.D. student at University of California, Berkeley. Poust is now postdoctoral researcher at the San Diego Natural History Museum.

Scientists named the dinosaur Wulong bohaiensis. Wulong is Chinese for “the dancing dragon” and references the position of the beautifully articulated specimen.

About the Discovery

The specimen was found more than a decade ago by a farmer in China, in the fossil-rich Jehol Province, and since then has been housed in the collection of The Dalian Natural History Museum in Liaoning, a northeastern Chinese province bordering North Korea and the Yellow Sea. The skeletal bones were analyzed by Poust alongside his advisor, Dr. David Varricchio, from Montana State University while Poust was a student there.

Larger than a common crow and smaller than a raven, but with a long, bony tail which would have doubled its length, Wulong bohaiensis had a narrow face filled with sharp teeth. Its bones were thin and small, and the animal was covered with feathers, including a wing-like array on both its arms and legs and two long plumes at the end of its tail.

This animal is one of the earliest relatives of Velociraptor, the famous dromaeosaurid theropod dinosaur that lived approximately 75 million years ago. Wulong’s closest well-known relative would have been Microraptor, a genus of small, four-winged paravian dinosaurs.

The discovery is significant not only because it describes a dinosaur that is new to science, but also because it shows connection between birds and dinosaurs.

“The specimen has feathers on its limbs and tail that we associate with adult birds, but it had other features that made us think it was a juvenile,” said Poust. To understand this contradiction, the scientists cut up several bones of the new dinosaur to examine under a microscope. This technique, called bone histology, is becoming a regular part of the paleontology toolbox, but it’s still sometimes difficult to convince museums to let a researcher remove part of a nice skeleton. “Thankfully, our coauthors at the Dalian Natural History Museum were really forward thinking and allowed us to apply these techniques, not only to Wulong, but also to another dinosaur, a close relative that looked more adult called Sinornithosaurus.”

The bones showed that the new dinosaur was a juvenile. This means that at least some dinosaurs were getting very mature looking feathers well before they were done growing. Birds grow up very fast and often don’t get their adult plumage until well after they are full sized. Showy feathers, especially those used for mating, are particularly delayed. And yet here was an immature dinosaur with two long feathers extending beyond the tip of the tail.

“Either the young dinosaurs needed these tail feathers for some function we don’t know about, or they were growing their feathers really differently from most living birds,” explained Poust.

An additional surprise came from the second dinosaur the scientists sampled; Sinornithosaurus wasn’t done growing either. The bone tissue was that of an actively growing animal and it lacked an External Fundamental System: a structure on the outside of the bone that vertebrates form when they’re full size. “Here was an animal that was large and had adult looking bones: we thought it was going to be mature, but histology proved that idea wrong. It was older than Wulong, but seems to have been still growing. Researchers need to be really careful about determining whether a specimen is adult or not. Until we learn a lot more, histology is really the most dependable way.”

“We’re talking about animals that lived twice as long ago as T. rex, so it’s pretty amazing how well preserved they are. It’s really very exciting to see inside these animals for the first time.”

Reference: “A new microraptorine theropod from the Jehol Biota and growth in early dromaeosaurids” by Ashley W. Poust, Chunling Gao, David J. Varricchio, Jianlin Wu and Fengjiao Zhang, 15 January 2020, The Anatomical Record.
DOI: 10.1002/ar.24343 [/cite]

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The tinniest dinosaur sesxribed in post #1: Source: https://www.scientificamerican.com/a...ound-in-amber/ is not likely dinosaur nor bird, but a lizard. Later comparitive anatomy research made the determination.

Source: https://syrianews.media/2020/08/04/scientists-retract-claim-of-finding-tiniest-dinosaur-nbc-news/

Scientists retract claim of finding tiniest dinosaur – NBC News
tanmay halaye

A spectacular fossil skull preserved in a drop of amber is not from a tiny flying dinosaur but probably the remains of an ancient lizard, according to a retraction of the original research published in March.

As NBC News had reported, the new species dubbed Oculudentavis, meaning eye tooth bird was thought to be just a few inches long, making it the smallest dinosaur ever found.
But the questions about the research and the discovery of a similar fossil have cast doubt on its classification as a bird-like dinosaur, and the authors agreed to a retraction in late July.
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Although the description of Oculudentavis khaungraae remains accurate, a new unpublished specimen casts doubts upon our hypothesis, the researchers wrote in the retraction in the journal Nature, which published the original research.
An artistic rendering of Oculudentavis imagining what it looked like preying on an insect.HAN Zhixin / Los Angeles Natural History Museum
Lizards and snakes are a different group of reptiles than dinosaurs. Both groups evolved from amphibians more than 300 million years ago, but then diverged from each other and although some lizards now look like dinosaurs, the closest relatives of dinosaurs living today are birds, which evolved from them directly.
Jingmai OConnor, a paleontologist at the Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and a co-author of the research, told Nature that data from new studies of the remains definitely say that we were wrong.
But she said the description of the new species remained accurate, and that it was still very interesting to science.
The fossil was found in 2016 in northern Myanmar, which has become a treasure trove of prehistoric animals preserved in amber the dried resin of ancient trees.
But its classification this year as a bird-like dinosaur was questioned by other paleontologists.

Oculudentavis has several features common to lizards of that era that had never been seen in bird-like dinosaurs; details of its teeth and the structure of its skull overwhelmingly support its squamate [lizard or snake] affinity, according to separate research posted on the internet but not yet published in an academic journal.
Retractions are a vital part of diligent scientific research; paleontologist Andrea Cau of Italys University of Bologna told Nature that such reclassifications were not uncommon, especially of incomplete fossil specimens from unknown groups.

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Source : https://www.nbcnews.com/science/scie...osaur-n1235659