Digital restoration of the brand-new Mesozoic bird fossil skeleton (scale bar: 10 mm). Credit: Min Wang
Researchers from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences have actually found a 120-million-year-old partial fossil skeleton of a small extinct bird that suits the palm of the hand and maintains a unique skull with a mix of dinosaurian and bird functions.
The two-centimeter-long (0.75 inch) skull of the fossil shares lots of structural and practical functions with the massive Tyrannosaurus rex, suggesting that early risers kept lots of functions of their dinosaurian forefathers and their skulls worked just like those of dinosaurs instead of living birds.
Their findings were released in Nature Communications on June 23, 2021.
The bird was transferred 120 million years earlier in a shallow lake in what is today Liaoning Province in northeastern China.
Through comprehensive restoration of the bird ancestral tree, the scientists showed that the brand-new fossil bird types comes from an extinct group of birds called enantiornithines, or “opposite birds.” They are the most varied group of birds from the time of the dinosaurs in the Cretaceous and have actually been discovered all over the world.
Digital restoration of the brand-new Mesozoic bird skull with broadened information of the dinosaur-like palatal bones, i.e., the basisphenoid (red), pterygoid (pink), and quadrate (purple). The stars show the 2 parts of the pterygoid prong that extend behind the eye. Credit: Min Wang
In living birds, the quadrate is among the most movable bones in the skull and permits the distinct function of living birds called “kinetic skull,” which enables the upper jaw to move individually of the brain and the lower jaw.
In contrast with living birds, nevertheless, the skull of this brand-new “opposite bird,” along with those of dinosaurs like Tyrannosaurus rex and the close dinosaurian family members of birds (e.g., troodontids and dromaeosaurs), is not kinetic. Instead, its bones are “locked up” and not able to move.
The temporal areas (sides) of the skull of this bird fossil are really various from living birds. This brand-new types has 2 bony arches for jaw muscle accessory like those discovered in reptiles such as lizards, alligators, and dinosaurs, making the back of the skull stiff and resistant to motion amongst the bones.
“When reconstructing all parts of the skull three-dimensionally from the high resolution CT scans of the fossil, I had a problem figuring out one bone in particular,” stated Dr. Min Wang, the lead and matching author of the research study. He stated his associate Dr. Thomas Stidham proposed that the bone was the pterygoid and looked “precisely like that of the dromaeosaur Linheraptor.” The fossil has the very first unspoiled pterygoid bone discovered in an early riser.
The scientists compared CT scans of the bird skull to scans of the skull of the widely known dromaeosaur Linheraptor from Inner Mongolia, China. The results revealed that lots of other functions of the rear part of the skull, consisting of the shape of the basisphenoid bone and its connections with other skull bones, likewise look like dromaeosaurs instead of living birds.
“The fossil bird and dinosaurs also lack the discrete contact between the pterygoid and quadrate near the palate that is used in skull kinesis in living birds. In combination with the ‘locked up’ temporal bones, the difference in the palate structure also points to the absence of kinesis among early birds,” stated Dr. Stidham, co-author of the research study.
Furthermore, the group’s discovery and careful physiological research study aid to strengthen the currently well-supported contention, based upon various lines of proof, that birds are not just living dinosaurs, however progressed from the branch of dinosaurs that consists of troodontids and dromaeosaurs like the “four-winged” Microraptor and swift Velociraptor.
“Having a ‘dinosaur’ skull on a bird body certainly did not stop the enantiornithines, or other early birds, from being highly successful in places all around the world for tens of millions of years during the Cretaceous,” stated Dr. Wang.
Reference: “Cretaceous bird with dinosaur skull sheds light on avian cranial evolution” by Min Wang, Thomas A. Stidham, Zhiheng Li, Xing Xu and Zhonghe Zhou, 23 June 2021, Nature Communications.
DOI: 10.1038/s41467-021-24147-z
