Scientists have discovered the most complete bird fossil ever found in Burmese amber.
The remains of a 99 million-year-old Enantiornithes baby bird, uniquely preserved, were found in a piece of Burmese amber from Myanmar. According to the scientists who published the corresponding article in the journal Gondwana Research, this is the most complete bird fossil ever found in Burmese amber, but for its full study, they had to resort to computed tomography methods.
Originally, the small 9-centimeter piece of amber containing fossils was found by amber collectors in the Yukon Valley in northern Myanmar. In 2014, it was acquired by the director of the Chinese Amber Museum in Tengchun City (Yunnan Province). The find was kept there for some time.
The visible part of the fossil looks like the paw of some strange lizard, and only experts were able to discern in it a bird’s paw from the time of the dinosaurs.
Additional CT images showed the remarkable degree of preservation of the part of the find that remained invisible behind the opaque layers of amber, which also contained plant remains, clay particles, and accumulations of air bubbles.
What did researchers learn about evolution from the 99-million-year-old baby bird preserved in Burmese Amber?
The surviving feathers made it clear that the chick died during its first molt – it found itself walled up in amber during the first days or weeks of his life.
It is noteworthy that the appearance of feathers from the wings of a chick shows that it was capable of flight almost immediately, as soon as it hatched from an egg, which is not at all like most modern birds that need long-term nursing from caring parents.
The hatching belonged to one of the main groups of birds that once coexisted with dinosaurs and died out together with them at the end of the Cretaceous 65–66 million years ago – the so-called Enantiornithes birds. The new discovery made it possible to obtain important information about these ancient toothed birds and their differences from modern birds.
The reconstruction of the fossil shows the chick in the position in which he accepted his death, stuck in the tree resin – literally frozen in time. By simulating the process of its molting, the researchers were able to determine the color of the 99-million-year-old feathers – it varies from white and brown to dark gray, so paleontologists nicknamed the found chick Belone – from the Burmese name of the local species of larks.
The remains of Enantiornithes birds have been found on all continents, with the exception of Antarctica; more than 60 species have already been described. In the Cretaceous period, they successfully settled the then-existing continents – Laurasia and Gondwana, lived mainly in forests, but some representatives of the group also settled on the shores of reservoirs.
The Enantiornithes got their name because they are in many ways the opposite of modern (fan-tailed) birds, and in the most paradoxical way. They were distinguished by the presence of teeth instead of a beak, and claws on the wings, and the humerus, which was attached in the opposite, protracted position. And somehow they managed to fly successfully.
The shell of their eggs was distinguished by a strong three-layer structure. At the same time, previous finds of individual wings of Enantiornithes birds in amber showed feathers that are surprisingly similar in structure to the flight feathers of modern birds.
Examining a new specimen, scientists found that the Enantiornithes calf already had a full set of flight feathers on its wings, but the rest of its plumage was sparse and looked more like filamentous feathers of theropod dinosaurs, which do not have a clearly defined central core. The presence of flight feathers on such a young bird confirms the idea that Enantiornithes birds hatched immediately with the ability to fly.
However, this advantage came at the price of slow growth rates, which made these ancient birds more vulnerable over a longer period of time, as evidenced by the large number of juvenile Enantiornithes fossils found in the past.
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• Blakemore, E. (2017, June 08). This 99-million-year-old bird coexisted with dinosaurs.
• Rafi Letzter, T. (n.d.). 99-Million-Year-Old dinosaur bird WINGS found preserved in amber.
• Xing, L., McKellar, R., Wang, M., Bai, M., O’Connor, J., Benton, M., . . . Xu, X. (2016, June 28). Mummified precocial bird wings IN MID-CRETACEOUS Burmese amber.
• Xing, L., O’Connor, J., McKellar, R., Chiappe, L., Tseng, K., Li, G., & Bai, M. (2017, June 06). A mid-Cretaceous ENANTIORNITHINE (AVES) HATCHLING preserved in Burmese amber with unusual plumage.