Early bird that likely lost the ability to fly described in China — ScienceDaily

In Fujian Province in southeastern China, paleontologists discovered a fossil species of early bird, Yuezhuornis yangyuanensis, which lived in the Late Jurassic 150–148 million years ago. According to the researchers’ conclusions, the bird, about the size of a crow, likely lost the ability to fly and adapted to life on the ground. ScienceDaily reports on the discovery.

A combination of bird and dinosaur traits

The fossil species combined anatomical features characteristic of birds with traits of small predatory dinosaurs. Its jaws had densely packed serrated teeth similar to those of deinonychosaurs, a group of carnivorous dinosaurs related to birds.

A distinctive feature was its second toe: it could bend unusually far backward and had a curved, sickle-shaped claw. This structure is associated with deinonychosaurs, including dromaeosaurids and troodontids. At the same time, the pelvis and hind limbs of Yuezhuornis had bird-like features.

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An early branch of bird evolution

The researchers used two methods to establish the species’ evolutionary position: maximum parsimony analysis and Bayesian dating based on fossil remains. Both approaches placed Yuezhuornis within Avialae, a group that includes modern birds and their closest extinct relatives.

According to the analysis, the species was positioned on the evolutionary tree somewhat closer to modern birds than Archaeopteryx and was a sister taxon to Zhengheornis. The proportions of its limbs were found to be similar to those of modern ground birds and some related dinosaurs. According to the study’s authors, this indicates a terrestrial lifestyle and a likely inability to fly.

The remains were found in the Zhenghe fauna, a fossil assemblage in Fujian that researchers consider important for studying a poorly researched stage of early bird evolution.