Life reconstruction of the 150-million-year-old avialan theropod Fujianvenator prodigiosus. Credit score: Chuang Zhao

A brand new 150-million-year-old avialan theropod, Fujianvenator prodigiosus, has been found in China, providing contemporary insights into early chook evolution and the Late Jurassic terrestrial ecosystem.

Birds descended from theropod dinosaurs by the Late Jurassic, however our understanding of the earliest evolution of the Avialae, the clade comprising all fashionable birds however not Deinonychus or Troodon, has been hampered by a restricted range of fossils from the Jurassic. (A clade is a bunch of organisms that consists of a single widespread ancestor and all its lineal descendants, representing a single department on the “tree of life.”)

As of now, no definitive avialans have been reported besides the Center–Late Jurassic Yanliao Biota in northeast China (166–159 million years in the past; Ma) and the marginally youthful German Solnhofen Limestones, which protect Archaeopteryx. Consequently, there’s a hole of about 30 million years earlier than the oldest recognized report of Cretaceous birds. Nonetheless, the Jurassic avialans are key to deciphering the evolutionary origin of the attribute avialan physique plan. Extra importantly, they’re key to reconciling the phylogenetic controversy in regards to the origin of birds.

{Photograph} and interpretive line drawing of the 150-million-year-old avialan theropod Fujianvenator prodigiosus, with a phylogeny and paleomap displaying the locality of the Zhenghe Fauna (purple star). Credit score: Min Wang

A New Discovery

A joint analysis staff from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese language Academy of Sciences in Beijing and the Fujian Institute of Geological Survey (FIGS) described and analyzed a brand new 150-million-year-old avialan theropod from Zhenghe County, Fujian Province.

The findings had been printed in Nature on September 6.

The brand new species, named Fujianvenator prodigiosus, reveals a weird meeting of morphologies which can be shared with different avialans, troodontids, and dromaeosaurids, displaying the influence of evolutionary mosaicism in early chook evolution.

Morphometric house of physique plan and cursoriality of Fujianvenator prodigiosus, in contrast with different Mesozoic theropods. Credit score: Min Wang

Fujianvenator’s Distinctive Morphology

“Our comparative analyses present that marked modifications in physique plan occurred alongside the early avialan line, which is essentially pushed by the forelimb, ultimately giving rise to the everyday chook limb proportion,” mentioned Dr. Min Wang from IVPP, lead and corresponding creator of the examine. “Nonetheless, Fujianvenator is an odd species that diverged from this principal trajectory and advanced weird hindlimb structure.”

The surprisingly elongated decrease leg and different morphologies, together with different geological observations, recommend that Fujianvenator lived in a swamp-like surroundings and was a high-speed runner or a long-legged wader, representing a beforehand unknown ecology for early avialans.

Stratigraphic log and vertebrate fossil assemblage found within the Late Jurassic Zhenghe Fauna. Credit score: Min Wang

Geological Context and Implications

“Moreover Fujianvenator, we’ve got discovered ample different vertebrates, together with teleosts, testudines, and choristoderes,” mentioned Liming Xu from FIGS, lead creator of the examine.

Through the Late Jurassic–Early Cretaceous, southeastern China underwent intensive tectonic actions as a result of subduction of the paleo-Pacific plate, leading to widespread magmatism and coeval fault-depression basins, the place Fujianvenator was discovered. This geological background is actually the identical as within the Late Jurassic in north and northeastern China, the place the older Yanliao Biota is preserved.

“The extraordinary range, distinctive vertebrate composition, and paleoenvironment strongly point out that this locality paperwork a terrestrial fauna, which we named the Zhenghe Fauna,” mentioned Dr. Zhonghe Zhou from IVPP, co-author of the examine. In-situ radioisotopic relationship and stratigraphic surveys constrain the Zhenghe Fauna to the interval from 150–148 Ma. Due to this fact, Fujianvenator paperwork one of many stratigraphically youngest and geographically southernmost members of the Jurassic avialans.

The invention of the Zhenghe Fauna opens a brand new window into the Late Jurassic terrestrial ecosystem of the planet, and the joint analysis staff from IVPP and FIGS plan to proceed their exploration of Zhenghe and close by areas.

Reference: “A brand new avialan theropod from an rising Jurassic terrestrial fauna” by Liming Xu, Min Wang, Runsheng Chen, Liping Dong, Min Lin, Xing Xu, Jianrong Tang, Hailu You, Guowu Zhou, Linchang Wang, Wenxing He, Yujuan Li, Chi Zhang and Zhonghe Zhou, 6 September 2023, Nature.
DOI: 10.1038/s41586-023-06513-7