“Like a chicken”: the strange fossil that would explain how dinosaurs became birds

millions of years ago, birds descended from theropod dinosaurs of the late Jurassic, but including How did this development take place? still not quite clear due to the lack of Jurassic fossils.

Avian dinosaurs are the origin of the birds we know today, but there is a gap of about 30 million years before the first known sighting. THE the avians of Jurassic are a key species to decipher the origin of birds each finding is therefore relevant to the investigation.

Today, a group of Chinese paleontologists discovered in Fujian province, China, a Avian theropod fossil from 150 million years ago. Simply put, it is a kind of bird-like dinosaur that inhabited the Earth in the late Jurassic period.

The new species has been dubbed futijianvenator prodisgiosus, which translates into Spanish as “strange hunter from Fujian”. The fossil has a composition of elongated legs, twice as long as its thighs and about the size of a pheasant a type of bird belonging to the chicken family, experts estimate it weighed around 641 grams.

The finding from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences in Beijing and the Fujian Institute of Geological Survey (FIGS) was published in the journal Nature September 6.

The discovery of this rare fossil is significant because it fills a gap in the fossil record close to the origin of birds, said Min Wang, lead author of the study. Fujian HunterGiven their unique skeletal morphology, sheds new light on morphological evolution at the very beginning of bird evolution “, he pointed out.

According to Nature, the fossil found lacks a complete head and tail, but the rest of the body has similar characteristics to other bird-like dinosaurs, such as details of its bone structure and the length of its fingers. .

“Our comparative analyzes show that marked changes in body plan occurred throughout the first avian lineage, which is largely driven by the forelimbs, eventually giving rise to the typical limb proportion of birds,” Min Wang said in a statement. release .

Observation of its geological and morphological characteristics, such as a surprisingly elongated leg and more specialized grasping fingers, indicate that it could not have had the ability to fly, but rather was a runner. high speed.

But it is also a characteristic present in waders such as storks and cranes, which allows fujianvenator lived in a swamp-like environment presenting a hitherto unknown ecological niche for early avians.

The Fujianvenator Basin has features that are more dinosaur-like that are less bird-like. This means that the morphological transition from arms to wings began very early in the ancestors of birds, while the legs were still doing different things, and suggests that Fujianvenator branched off in a different direction than the one that led the birds.

“The Fujianvenator is a rare species that deviated from this main trajectory and evolved with a strange hind leg architecture,” Min Wang said.

But, “to find out whether the bird’s legs were an adaptation to living in swamps or running at high speed, researchers will have to examine the tips of his toes for signs of webbing, but those toes are poorly preserved Nature explained.

The fact that the fossil was discovered is a real stroke of luck. Researchers discovered it at a site near Nanping, Fujian province, where dinosaurs had never been found before. And examples of bird-like dinosaurs from the Late Jurassic are rare because their hollow bones are fragile and less well preserved. Fossilization requires ideal conditions, such as the absence of oxygen, to prevent decomposition, conditions that lakes or swamps can provide.

But during the Upper Jurassic and Upper Cretaceous, the southeast China has experienced intense tectonic activity that has resulted in widespread magmatism and contemporaneous faulting low basins, where Fujianvenator was found, which allowed for the preservation of the fossil.

In addition to the Fujianvenator, the researchers discovered other vertebrates such as fish, turtles and other aquatic reptiles. “The extraordinary diversity, unique vertebrate composition and paleoenvironment clearly indicate that this locality documents a terrestrial fauna, which we call the Zhenghe fauna,” said study co-author Dr. Zhou Zhonghe of IVPP. .

Fujianvenator Documents one of the stratigraphically youngest and geographically southernmost members of the avians of the Jurassic. This discovery opens a new window into the Late Jurassic planet’s terrestrial ecosystem, and there is still much to discover about the new species.