[Reading Science] Is Archaeopteryx No Longer the Original Bird?

Chinese Fujian Geological Survey Institute Discovers New Ancestor Fossil of Birds
"Evidence That Diverse Species Had Already Diverged 150 Million Years Ago"

It is commonly known that the ancestor of birds was Archaeopteryx, which lived about 150 million years ago. However, a newly discovered fossil is attracting attention by challenging this common knowledge. It suggests that birds did not evolve from Archaeopteryx but were already evolving in complex and diverse forms beforehand. This adds new evidence to the claim that birds are not evolved from dinosaurs but are a lineage of "surviving dinosaurs."

Archaeopteryx Fossil

A research team from the Fujian Geological Survey Institute in Fujian Province, China, published a paper on the 6th (local time) in the international academic journal Nature, reporting the discovery of a new type of avian theropod fossil.

Although most dinosaurs went extinct about 66 million years ago, it is the established academic theory that theropods?bipedal dinosaurs such as Velociraptor and Tyrannosaurus rex, which had three claws and hollow bones making them lightweight?evolved into today's birds. In particular, most scholars believe that feathered dinosaurs, i.e., birds, first appeared about 150 million years ago based on the Archaeopteryx fossil discovered in a German mine in 1861.

However, the research team analyzed a fossil of an avian dinosaur named Fujianvenator prodigiosus, excavated in 2022 near Nan'ning in southeastern Fujian Province, China, and found something unusual. This dinosaur is estimated to have lived around the same time as Archaeopteryx, about 150 million years ago, but strangely, it had slender and long legs below the knees, suggesting it could run fast but likely had no flying ability.

Based on this, Nature pointed out, "Additional evidence has been found that avian dinosaurs began to diversify into different types during the period when Archaeopteryx was already living."

The fossil of Fujianvenator excavated by the research team lacks parts of the head and tail, with only the torso and limbs remaining. However, it has several features similar to other avian dinosaurs, such as long finger lengths and the shapes of the pelvis and spine.

However, the team's analysis showed that the overall skeleton of Fujianvenator was not structured for flight like birds. Notably, the scapula was short, and the structure and shape of the fingers were more specialized for grasping prey rather than flying. The most distinctive feature was Fujianvenator's excessively elongated legs. The tibia (the lower leg bone below the knee) was twice as long as the femur (thigh bone). This leg structure indicates that Fujianvenator could run quickly on land. It is similar to the roadrunner (scientific name Geococcyx), a bird that is not a strong flyer but can run at speeds of about 22 km/h on land.

Alternatively, Fujianvenator's leg structure might have evolved to adapt to slippery environments while hunting in swamps. In fact, fossils of fish, turtles, and other aquatic reptiles were found together at the Zhanghe fossil site where Fujianvenator was excavated. To determine whether Fujianvenator's unusual leg structure was an adaptation to swamp life or for high-speed running, researchers would need to examine whether there are traces of webbing at the tips of its toes. Unfortunately, the fossil lacks the toe tip parts entirely, leading to various interpretations.