Nandu News reporter Yang Liyun, the smallest dinosaur in history about 99 million years ago, was recently discovered, and this dinosaur was even smaller than the smallest living bird (hummingbird)!
On March 12, a team of Chinese and American Canadian scientists announced in Beijing that they had found the smallest dinosaur ever found in Burmese Cretaceous amber (broad dinosaurs including birds).
< h1 toutiao-origin="h6" > oculophore amber</h1>
This discovery has important implications for understanding the evolution of dinosaurs and ancient birds, especially the morphological evolution of miniaturized animals. The study was published in the journal Nature, a comprehensive academic journal.
The smallest dinosaur fossil was found in Myanmar
The amber fossils found this time are from the Hugang Valley in Kachin State in northern Myanmar, and geologists have determined the geological age of volcanic ash zircon isotopes in the mine, believing that the amber in the Hugang Valley was formed about 100 million years ago (about 99 million years), belonging to the middle Cretaceous Period (the earliest of the late Cretaceous), which is considered to be the best window for humans to glimpse the "real" Cretaceous world.
< h1 toutiao-origin="h6" > the amber mining area of northern Myanmar</h1>
Birds are descendants of dinosaurs and are among the most biodiverse vertebrates, with about 10,500 species. In the long evolutionary history of nearly 150 million years, there have been two radiation evolutions in the Cretaceous and Cenozoic, of which the Cretaceous is an important stage in the evolution of birds and one of the key stages in the evolution of birds from dinosaurs. The bird amber inclusions in the Hugang Valley are relatively rich, which is very helpful for understanding bird evolution.
It is difficult to classify because of the skeletal characteristics of the "four unlikeness"
Scientists have created new genera and new species for this purpose
The specimen of the study is a complete animal skull wrapped in amber, and the first challenge in conducting the study was how to obtain complete, high-resolution 3D information about the skull surrounded by layers of amber, fur and impurities without compromise.
Li Gang's team used the Shanghai Light Source (SSRF) hard X-ray imaging line station and the high-modulation transfer function (MTF) high-efficiency hard X-ray detector they developed at the Beijing Synchrotron Radiation Facility (BSRF), and then through phase recovery, tomography, data fusion and virtual segmentation of specific structures, and finally obtained the high-resolution high-contrast 3D structure of the skull hidden inside the amber without loss.
< h1 toutiao-origin="h6" > CT reconstruction of the head of the oculodonted bird</h1>
<h1 toutiao-origin="h6" > eyetooth bird head restoration diagram drawing Han Zhixin</h1>
The skull in amber is only about 14 mm long, with a sharp beak, dense teeth, and huge eye sockets. The skeletal characteristics of this animal are somewhat "four different", some are like dinosaurs, and some are like very high-class birds. Scholars have not found specific skull features to classify the bird as a bird, non-avian dinosaur, or other dominant dragon. Even scholars cannot completely rule out that this skull belongs to other animals. Scholars who have studied the specimen say it is so strange that it is difficult to determine the specific category. "This is the strangest fossil I've ever had the pleasure of studying," Ms. Zou said. However, among vertebrates, only birds have both a sharp beak and a huge eye socket, so scholars attribute the animal to birds.
Given that the morphological characteristics of the specimen differ from all other birds, scholars established a new genus, the Oculudentavis khaungraae, which indicates the characteristics of the specimen, the large eyes and dense teeth, and the species name Kwanya paid tribute to ms. Kwanya, a Burmese amber collector who first discovered and collected this specimen. The specimen belongs to the Amber Pavilion Museum in Tengchong, Yunnan and the Yangon Branch museum in Myanmar, and was collected from the northern Myanmar mining area in 2016 by the curator, Mr. Chen Guang, and his family, Ms. Kuanya.
The eye-toothed bird is the smallest ancient bird
It is also the smallest dinosaur in history
We know that the smallest living bird is the hummingbird, and the smallest hummingbird is the Mellisugahelenae, which weighs about 1.95 grams and is 5.5 centimeters long, making it the smallest bird in the world. In terms of skull size, the eye-toothed bird is shorter than the hummingbird, the smallest ancient bird ever found, and the smallest dinosaur in history.
About 100 million years ago, the eye-toothed bird lived in the humid tropical environment of northern Myanmar, unfortunately wrapped in resin flowing from conifers such as cypress or araucaria, which formed amber over a long geological age and has been preserved to this day. Tens of millions of years later, this little bird's bad luck has achieved good luck for paleontologists. The advantage of amber is that it provides an unparalleled state of preservation for paleontology.
<h1 toutiao-origin="h6" > eyetooth bird habitat restoration diagram Han Zhixin</h1>
The total number of teeth adds up to about 100
The most interesting thing about the eye-toothed bird is its miniaturization. Animals that have become so small have to face many new problems, such as how to integrate all the sensory organs into their tiny heads, how to maintain body temperature, and so on.
This miniaturization process usually occurs in isolated environments, most typically islands. It just so happened that Burma was an isolated island arc in the middle of the Cretaceous Period. Miniaturization is often accompanied by features such as tooth loss and enlarged eyes.
However, despite the small size of this specimen, it has more teeth than all other ancient birds. The dentition is also longer than other birds and extends under the eye. There are 18–23 teeth on each side of the upper jaw, 29–30 teeth on each side of the dental bone, and about 100 teeth in total! This is also the reason why scholars have named it the eye-toothed bird. The large number of teeth tells us that despite its super small size, it is a carnivorous animal.
The active mode is daytime
Another peculiarity of the oculodonted bird is its eye area, which is about 4 mm in diameter. Birds and most reptiles (including dinosaurs, pterosaurs, and ichthyosaurs) have a sclera ring consisting of scleral ossicles that surround the eyeball in the middle and support and protect the eyeball.
The scleral ossicles in birds are square and very simple, but the scleral ossicles of the eye-toothed birds are spoon-shaped, a form that has only been found in some living lizards, which is one of the places that has greatly puzzled researchers.
However, the eye-toothed bird's eyes are also different from birds with developed sclera rings such as owls, with the owl's eyes facing forward and the eye-toothed birds facing the sides. The cheekbones of the bird are curved and the eyes protrude from the side of the head. This visual system is never found in living animals, which makes it difficult to understand how its eyes work. In addition, the opening of the eye bone (the inner diameter of the eye circle) indicates that the activity pattern of the oculodental bird is daytime.
Has a long tail
The phylogenetic relationship between the oculodonted bird and other birds is also special. Analyzed from the skull alone, this newly discovered tiny bird, the eye-toothed bird, is very primitive, between archaeopteryx, the most primitive archaeopteryx of the Late Jurassic of Germany, and the long-tailed Jeholornis of China's Early Cretaceous. This may indicate that, like both taxa, the oculodonted bird had a long tail similar to that of a non-avian dinosaur.
All in all, the size and morphology of the bird shows us a new class of body structures and the ecology it represents. The discovery highlights the potential of amber deposits to reveal the smallest vertebrate size. However, since the oculodonted bird specimen has only a head, there is still some uncertainty in its classification. Scholars will continue to search in Memper, hoping to find more complete individuals in the future and uncover the full secrets of the eye-toothed bird.
The study was published in the journal Nature
The study was conducted by Associate Professor Xing Lida of China University of Geosciences (Beijing), Jingmai K. O'Connor, Foreign Researcher at the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Ph.D. Lars Schmitz of the Natural History Museum in Los Angeles, Li Gang, Researcher Li Gang of the Institute of High Energy Physics, Chinese Academy of Sciences, and Professor Luis M. Chiappe, Dean of the Dinosaur Research Institute at the Museum of Natural History, Los Angeles, USA. Professor Ryan C. McKellar of the Royal Museum of Saskatchewan, Canada, and Dr. Yi Qiru, Beijing Center for Comprehensive Research, Chinese Academy of Sciences, and other scholars jointly completed the work. The research paper is entitled "Burmese Cretaceous Hummingbird Large Dinosaur" published in the journal Nature, a comprehensive academic journal.