Paleontologist Ming Wang of the Chinese Academy of Sciences and colleagues compared the new fossil, called Fujianvenator prodigiosus, with the remains of other dinosaurs from that period and more recently to determine its place in the animal’s family tree. The researchers say it belongs to the ancestral group Avialae, which includes modern birds and their closest dinosaur ancestors.

What is known about the new species

Remains of such early bird ancestors are hard to find, so each one holds important clues to their evolution and the environment in which they lived.

Until now, scientists considered the remains of the 150-million-year-old dinosaur Archeopteryx a critical early point in the evolution of modern birds. Today, however, researchers aren’t sure if it should be classified as Avialae, and they call the alternative group Deinonychosauria (a series of theropod dinosaurs that lived from the mid-Jurass period to the late Cretaceous). According to fossil evidence, Archeopteryx already had feathers.

Appearing only a few million years after Archeopteryx, Fujianvenator may provide at least a few answers, straddling the line between ancient dinosaurs and more modern birds. Fujianvenator prodigiosus was the size of a pheasant and probably had feathers. On its forelimbs, it exhibits features that are less birdlike and more dinosaur-like, including the odd four-winged Anchiornis. This means that in the ancestors of birds, the morphological transition from arms to wings began at a very early age, while the legs are still performing their normal functions.

Our comparative analysis shows that marked changes in body plan occurred throughout the first lineage of Avialae, largely defined by the forelimbs, eventually leading to typical avian limb proportions.
– scientists explain.

Fujianvenator prodigiosus / Photo: Zhao Chuang

But Fujianvenator is a strange species that has deviated from this basic orbit and has developed a peculiar rear-leg architecture. Presumably, its evolution went in a different direction from that which led to the emergence of modern birds. The elongated lower hind legs and the fossils they were found in indicate that the ancestor was a long-legged swamp dweller or a fast runner. For now, they can’t say for sure, because the legs are used in the same proportions for walking and running, so more fossils are needed for more accurate information.

If Fujianvenator prodigiosus is confirmed to live in swamps, this will be the first such case, as all other representatives of Avialae have the characteristics of tree dwellers.