Hundred million years ago, ferocious ancient birds had very strong toes
On October 30, a team of Chinese and foreign scientists found a very special fossil of ancient birds in Myanmar amber. Its details are of great significance for people to understand the diversity of ancient birds and the evolution of feathers. The research was led by Xing Lida, associate professor of China University of Geosciences (Beijing), Niu Kecheng, executive director of Yingliang world stone natural history museum, Ruian & middot, Royal Museum of Saskatchewan, Canada; Professor mckeller, Zou Jingmei, an American researcher at the Institute of Paleovertebrates and Paleoanthropology, Chinese Academy of Sciences, and other scholars jointly studied it. The research paper was published in the international well-known academic journal and the scientific report of nature group.
In 2016, Xing Lida's team found the world's first ancient bird wings and dinosaurs in amber, and then found nestlings, intact ancient birds, frogs and snakes in amber. " In the past three years, Myanmar amber about 100 million years ago has produced a series of immature anti bird bone fossils, with different development stages and integrity. With the discovery of more and more fossils, this hugang ancient bird fauna is gradually taking shape, which has greatly deepened our understanding of ancient birds, especially anti birds. " Xing Lida introduced.
The research specimens of scholars come from the famous amber producing area - hukang River Valley, Kachin state, northern Myanmar. Hukang River Valley is located in the northernmost part of Myanmar and the upper reaches of the qindun river. It is composed of daruo basin and xinpingyang basin. It has high mountains and dense forests, vertical and horizontal rivers and flooding in the rainy season. In Myanmar language, it is "the place where the devil lives". The locals call this uninhabited area hundreds of miles collectively "savage mountain". The amber here is about 100 million years old and provides a unique forest ecosystem record.
The newly discovered ancient bird amber is collected by Yingliang world stone natural history museum in Quanzhou, Fujian Province. Yingliang specimen does not preserve many foot bones, but the outline of bird feet is recorded by detailed skin, and there are a lot of hairs on the surface of these ancient bird foot skin. In addition, the specimen also preserved a very rare shaft dominated feather.
Yingliang bird's foot is about 7 mm long. Micro CT provides a detailed and three-dimensional three-dimensional anatomical structure for this small specimen. Through the proportion of feet and feather morphology, the researchers classified this specimen as anti bird. The overall shape of the foot and the curvature of the well preserved horny sheath strongly suggest that it is a arboreal bird. " Specifically, Yingliang specimen has large and curved claws, flat claws, and the cross-sectional morphology is similar to that of living arboreal birds, but different from terrestrial birds; Secondly, the distal phalange of the specimen is relatively long, which is a characteristic of arboreal birds, while the proximal phalange of terrestrial birds is long. " Xing Lida explained.
The most interesting thing about the new specimen is that its toes are very strong, which is different from all previously found bird fossils in the region. The outer toe, the fourth toe, has a laterally elongated toe pad, which is very strong relative to the two inner toes (the second and third toes). Simply put, the fourth toe is wider than the second or third toe, and its prominent foot pad and raised plantar surface may be related to catching prey. The strong toes with claws are similar to the living Raptor, which may indicate that Yingliang specimen is a small aerial insectivorous bird.
In addition, Ryan & middot; Professor mckeller told reporters: 'in the specimens we described this time, horny scale filamentous feathers are retained in each toe, and the densest and longest are at the base of the second toe. Horny scale filamentous feathers are rare in the nestlings of modern birds and do not seem to exist in adults. The horny scale filamentous feathers of this specimen may play a tactile role to help it catch small prey such as insects. " So far, horny scale filamentous feathers have been found on the feet of all anti birds found in the hugang group, and seem to be more obvious in older individuals or more developed in some species.
The feather shaft dominated feather in amber was a new discovery made by Xing Lida's team at the end of 2018. Its biggest feature is the open feather shaft, which forms an efficient light tail feather. In other words, the opening of the feather shaft may be a measure to save energy and reduce the energy consumption for growing such long feathers, or this structure is specially evolved for long and light tail feathers. Paleontologists now believe that the feather shaft dominated feather is a tool for intraspecific information exchange of ancient birds. Its main functions are courtship display, species identification and visual communication. " Previously, we found no bone material near the feather shaft dominated feather, but so far, only the remains of anti birds have been found in Myanmar amber, so these strange feathers are temporarily classified as anti birds. The specimen found this time is the first evidence that the feather shaft dominated feather can be directly corresponding to the anti bird remains. " Paleontologist Zou Jingmei said.
With regard to the burial of amber fossils, Niu Kecheng said that this inclusion contains bracts of cypresses, plant stellate hairs, a large number of particles, feces of insect larvae, and other uncertain plant leaf fragments. All these clues indicate that the resin block was formed near the forest ground. Moreover, when the bird's foot falls into the resin trap, it is still relatively fresh, because the resin around it has a thick layer of milky white material, and a large number of bubbles appear on the toe surface, which is a sign of corruption of fresh soft tissue.
The toe of Yingliang specimen is wider than any anti bird previously observed in Myanmar amber. This unique foot shape reflects the differences in the way birds capture prey. This type of foot has not been found in the local fossil record, which shows that the diversity of birds in the dinosaur era is far beyond people's imagination. More and more evidence shows that the hugang bird fauna is unique compared with other Cretaceous fauna.