They discover the fossil of a strange bird with a dinosaur head

A fossilized skeleton of a bird that lived in present-day China some 120 million years ago could help clarify key steps in the transformation process that led dinosaurs to become contemporary birds, which science has established are their direct descendants. The found fossil is a mysterious hybrid, which seems to integrate the characteristics of both species.

A new study by paleontologists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences describes a mysterious bird from the Cretaceous found in that Asian country, which shows evolutionarily decoupled skull and body. While the body is typical of birds, the head corresponds to that of a dinosaur. The research has recently been published in the journal Nature Ecology & Evolution.

From dinosaurs to birds

Although it is now widely accepted that birds descended from dinosaurs, this transition is also understood to encompass some of the most complex transformations from the morphological, functional and ecological point of view. Consequently, paleontologists are still trying to fully understand how this occurred. impressive evolutionary eventwhich led to the characteristic body plan of birds.

Now, the new complete fossil discovered in China, which is approximately 120 million years old, further complicates a possible way out of this problem: exhibits a skull similar to that of a dinosaur, articulated with a body similar to that of a bird. At the same time, the fossil named Cratonavis zhui preserves two even more intriguing features: a strikingly elongated scapula (bone located on the back and upper part of the thorax) and a first metatarsal (bone on the lower part of the leg), a condition that makes it stand out among all other birds, including the oldest fossils.

The researchers, led by paleontologist Zhou Zhonghe, discovered the fossilized remains of Cratonavis zhui during a series of excavations in northern China. Body footprints of feathered dinosaurs and primitive birds have been discovered in this region, in sedimentary rocks formed during the Cretaceous period.

Profound changes and transitions

According to one Press release, the scientists used high-resolution computed tomography (CT) and performed a digital reconstruction of the skull’s original shape and function. The result showed that the skull of Cratonavis zhui is morphologically almost identical to that of dinosaursspecifically that of a variety like the Tyrannosaurus rex, instead of being similar to that of a bird.

Meanwhile, primitive cranial features indicate that most Cretaceous birds, such as Cratonavis zhui, could not move their upper beak independently of the braincase and lower jaw. This functional innovation, widely distributed among contemporary birds, contributes to its enormous ecological diversity.

In the same vein, Chinese scientists have shown that the first metatarsal it was subject to selection during the dinosaur-bird transition, which favored a shorter bone. It then lost its evolutionary lability when it reached its optimal size, which is less than a quarter of the length of the second metatarsal.

Finally, the researchers concluded that the bizarre morphologies of the scapula and metatarsals preserved in Cratonavis zhui highlight the breadth of the skeletal plasticity acquired by the first birds. Apparently, these profound changes that led to the aves Current events were the result of the interaction between species development, natural selection, and ecological opportunity.